HaKadosh Baruch Hu created luminaries – the sun and the moon – and placed them in the heavens. They are the means by which we establish the order of time. The sun shines during the day, the moon at night. The order of years is determined by the cycle of the sun, and the months are based on the moon’s. As the Torah states: “God said, Let there be luminaries in the firmament of heaven to separate between the day and the night; and they will be for signs, and for appointed times, and for days and years”(Bereishit, 1:14).
Every month, the moon makes one orbit around the earth. This cycle is perceivable by the changes in the moon’s appearance. At the beginning of the month, the moon looks like a thin sliver. Gradually, it increases in size until the middle of the month, when it reaches its fullness, appearing as a complete circle. During the second half of the month, the moon wanes, until it completely disappears at the end of the month for approximately twenty-four hours. Afterwards, it reappears as a thin sliver, indicating that a new month has begun.
A full lunar cycle lasts 29½ days, plus, approximately, another three-quarters of an hour. Since this cycle does not coincide with the earth’s daily rotation around its axis, due to the extra half-a-day, a Jewish month lasts either twenty-nine or thirty days. A 29-day month is called an “incomplete month,” while a 30-day month is called, a “full month.”
Establishing the beginning of a month is extremely important, for all of our holidays depend on the Hebrew date: Passover commences on the fifteenth of Nisan, Yom Kippur falls out on the tenth of Tishrei, Sukkot begins on the fifteenth of Tishrei, etc. In fact, it is so important that the Torah permits witnesses who see the new moon to violate the Sabbath in order to travel to Jerusalem and give testimony before the Beit Din(Rambam, Kiddush HaChodesh 3:2). The Beit Din (rabbinic court) would sanctify the new month based on their testimony, and then dispatch messengers to inform all of Israel that the new month had begun.
 The exact duration is 29 days, 12 hours, and 793/ 1080 of an hour. The division of an hour into 1080 parts was designed to simplify complex calculations. All of this is explained in the Rambam’sHilchot Kiddush HaChodesh 6:1-3.
A new month does not automatically begin when the moon reappears. Rather, the judges of the Beit Din sanctify the month, as it says, “This month shall be for you” (Shemot, 12:2). HaShem showed Moshe Rabbeinu the configuration of the moon in its renewed state and said, “This testimony shall be given over to you” (Rosh HaShanah 22a). That is, witnesses must come before you (the judges) and testify that they saw the new moon, and you shall sanctify the month based on their testimony.
After Moshe Rabbeinu’s death, the authority to establish the Jewish calendar was conferred upon the high court of every generation, on condition that its judges had received rabbinic ordination (semichah) in an unbroken chain from Moshe Rabbeinu; and with the stipulation that such ordination can only be transmitted in Eretz Yisrael(Rambam, Hilchot Sanhedrin 4). If a time comes when the Jews are unable to fix the months by way of a Beit Din, the halachah states that they must do so using mathematical calculations.
Thus, even though the lunar cycle is a natural phenomenon, the renewal of the moon does not, by itself, sanctify the month. Rather, the Jewish people consecrate the months, and they cause the holiness within time to be revealed. This explains why our Sages decided to end the central blessing of the Musaf prayer on Rosh Chodesh with the words “Blessed are You, HaShem, Who sanctifies Israel and the beginnings of the months” (Berachot 49a). Perhaps this is also why the first mitzvah the Torah commanded the Jewish people was the mitzvah of sanctifying the new moon (Shemot, 12:2), for this mitzvah displays a facet of Israel’s unique sanctity – our ability to reveal the holiness within time.
 If witnesses who saw the new moon on the night of the thirtieth come before the Beit DinBeit Din the next day, the court would sanctify the month on that day, transforming the thirtieth day of the previous month into the first day of the new month, Rosh Chodesh. They would then immediately offer up the special Rosh Chodesh sacrifices. Consequently, the previous month would become an incomplete one, having only twenty-nine days. If, however, no witnesses arrive on that day (the thirtieth), it is clear that Rosh Chodesh will be the next day – the thirty-first – and the previous month was a full one, consisting of thirty days. In such a case, there is no need for the Beit DinBeit Din to accept witnesses or declare the beginning of the new month, for in any case there are only two possible days on which Rosh Chodesh can fall, and if no witnesses come on the first day, Rosh Chodesh will [automatically] fall out on the next day (Rambam, Hilchot Kiddush HaChodesh 2:8).
As a result of Roman persecution, the Jewish settlement in the Holy Land dwindled during the Talmudic period, while the larger community of Jews became ensconsed in Babylonia advanced in all areas. Nonetheless, the Sages of Eretz Yisrael retained the authority to sanctify months and intercalate years, as it says, “For out of Zion will go forth the Torah”(Yeshayahu, 2:3), and they dispatched messengers every month to inform the Jews residing in the Diaspora when the new month began. Only on rare occasions, like during the Beitar revolt, when the situation in the Holy Land was unbearable, and the Sages could not sanctify the months, judges ordained in Eretz Yisrael would leave the Land and journey to a place where the anti-Jewish decrees did not reach, in order to calculate the the months and the years.
Eventually, the Roman decrees intensified. As a result of Christian influence, decrees were aimed at the Sages in an attempt to stop them from sanctifying the months. During this period, the Rabbis of Eretz Yisrael sometimes had to sanctify a month while they were in hiding, and then inform the Sages of Babylonia by way of a secret letter (see Sanhedrin 12a).
Towards the end of the Talmudic period, Hillel the Second realized that the rabbinic courts of Eretz Yisrael would no longer be able to sanctify the months. He feared that hardships and evil decrees would lead to the termination of the institution of semichah. As Nasi, Hillel himself had the authority to fix the calendar, for he had inherited the presidency of the high court in a generational chain from Rabbi Yehudah HaNasi. Therefore, he and his fellow judges took the initiative and calculated the months and years forever, consecrated them in advance. Thus, in the year 4119 from creation (359 CE), the Jewish people began to count the months according to the Jewish calendar that Rabbi Hillel HaNasi established. We pray that we will soon be privileged to witness the final redemption, when the Beit Din in Jerusalem will once again sanctify the months.
The Rambam explains a very important concept, teaching that the sanctification of the months depends on the inhabitants of Eretz Yisrael, even after semichah was abolished. When the Jews of the Holy Land calculate the order of the months based on the fixed formula which Hillel used to establish the calendar, then the months are sanctified. If, however, no Jews lived in Eretz Yisrael, God forbid, the order of the months, along with all the holidays, would cease to exist. The Rambam adds, “God forbid that He should do such a thing, for He has promised us that the remnants of our nation will never be destroyed.
 The main idea is taken from the Rambam’s Hilchot Kiddush HaChodesh 5:1-3.
In Sefer HaMitzvot, Positive Commandment 153, the Rambam writes that the sanctification of the months is entrusted to the highest rabbinic court. The Ramban, however, claims that a Beit DinBeit Din of three will suffice. One could say that there is no argument here, for the Rambam means to say that the months are sanctified by virtue of the foremost court of the generation, [not that they actually have to do it].
As stated above, the months were sanctified in Eretz Yisrael, and only in dire circumstances did the greatest Rabbis of the generation, who were ordained in Eretz Yisrael, leave the Land in order to sanctify the months without interference from the hostile ruling kingdom. This is derived from a passage in Berachot 63a:
“When Chanina, R. Yehoshua’s nephew, went down to the Diaspora (after the Beitar revolt), he intercalated years and established months in Chutz LaAretz. [The Rabbis of Eretz Yisrael] sent two Torah scholars after him – R. Yosi ben Kippar and the grandson of Zechariyah ben Kevutal. When he saw them, he said, ‘Why have you come?’ They replied, ‘We have come to learn Torah.’ He proclaimed, ‘These men are [among] the greatest Rabbis of the generation, and their forefathers served in the Holy Temple…’ He began declaring [things] impure while they declared [them] pure. He forbade [certain acts] and they permitted [them]. [So] he announced, ‘These men are worthless; they are empty.’ They said to him, ‘You already built [us] up; you can no longer knock [us] down. You already built a fence; you can no longer breach it.’ He responded, ‘Why is it that whenever I declare [something] impure you declare [it] pure; whenever I forbid [something] you permit [it]?’ They answered, ‘Because you are intercalating years and establishing months outside the Land of Israel.’ He said, ‘Didn’t Akiva ben Yosef intercalate years and establish months in Chutz LaAretz?’ They replied, ‘Leave aside [the case of] Rabbi Akiva, for he did not leave behind anyone like him in Eretz Yisrael.’ He said to them, ‘I, too, left no one behind like me in Eretz Yisrael.’ They answered, ‘The kid-goats you left behind have become he-goats with horns, and they sent us to you, and this is what they told us, ‘Go, tell him in our names [to desist]. If he listens – fine. But if he does not – excommunicate him. And tell our brethren in the Diaspora [to desist as well]. If they listen – fine. But if not – let them go up to the mountain, [where] Achiyah will build an altar and Chananyah will play the harp, and everyone will deny [God], saying, “We have no portion in the God of Israel.’ [Upon hearing this], the entire congregation immediately burst into tears and said, ‘God forbid! We do have a portion in the God of Israel.’ And why all the fuss [not to establish the calendar in Chutz LaAretz]? Because it says, ‘For out of Zion will go forth the Torah, and the word of the Lord from Jerusalem’ (Yeshayahu 2:3).”
We stated above that when no ordained Rabbis exist, the months are sanctified by way of mathematical calculations. According to the Rambam, this is a halachah l’Moshe m’Sinai (a law given over to Moshe, by God, at Mt. Sinai). This is why he does not mention Rabbi Hillel HaNasi [in his discussion on the topic]. The Ramban, on the other hand, writes that there is no source for such a halachah l’Moshe m’Sinai. Rather, the truth is that in our times, as well, the months are sanctified by ordained Rabbis – that is, based on Rabbi Hillel’s calculations. Consequently, the Ramban does not require that there be Jews living in Eretz Yisrael so that the calculations can apply to them, for he holds that the months are not established based on the calculations of those currently living in Eretz Yisrael, rather, upon Rabbi Hillel’s ancient calculations. See Aruch HaShulchan 417:7.
When a month is incomplete (29 days), the following Rosh Chodesh is one day. When it is full (30 days), the following Rosh Chodesh lasts two days, the first day being the thirtieth of the previous month, and the second day being the first of the next month. Even though the second day is the main part of Rosh Chodesh – seeing that it is the first day of the month, from which we count the subsequent days of the month – nevertheless, all the laws of Rosh Chodesh apply to the first day, as well. We add the Additional Musaf Prayer , we recite Hallel, and we insert Ya’aleh VeYavo into our Amidah Prayers and Grace After Meals. One who forgot to say Ya’aleh VeYavo in Shacharit or Minchah must repeat the Shemoneh Esrei. Several explanations have been given for the practice of keeping two days of Rosh Chodesh; see the footnote.
Seemingly, one could ask: Rosh Chodesh means the first day of month; why then is the thirtieth day of a full month also considered Rosh Chodesh? The Shibolei HaLeket (168) quoting Rabbeinu Shlomo and the Rid (the earlier R. Yeshayah), as well as the author of Birkei Yosef (427), explain that when a month is full, the new moon appears in the middle of the thirtieth day (after 29½ days). Therefore, even though the next day will be the first of the month (in order to balance out the months, as explained above – 1.1), nonetheless, it is fitting to also treat the day on which the moon reappears as Rosh Chodesh. This is why we keep two days of Rosh Chodesh.
The Tashbetz (3:244) writes that the Jews in ancient times used to refrain from work, and prepare festive meals in honor of Rosh Chodesh, and they would begin doing so already on the thirtieth day of the month, in the event that witnesses arrive and the Beit Din declares that day the first of the month. And if no one came to testify, they treated the next day as Rosh Chodesh as well. Thus, whenever a month was full, they kept two days of Rosh Chodesh (similar to Rosh HaShanah). Even though the Musaf sacrifices were offered up exclusively on the first of the month, these two explanations indicate that both days are holy, and we therefore say Hallel, Musaf, and Ya’aleh VeYavo on both days.
Rabbi Zevin writes in LeOr HaHalachah (in an essay on Rosh Chodesh) that according to Rashi and the Shiltei Giborim (Rosh HaShanah, chap. 1), Jews used to keep one day of Rosh Chodesh on a full month, while the Or Zarua (vol. 2, Hilchot Rosh Chodesh) and the Maharsha (Bava Metzia 59b) maintain that they kept two days.
These authorities also disagree on how to interpret a verse in the First Book of Shmuel (20:27): ויהי ממחרת החדש השני. The Tashbetz and Rabbeinu Yeshayah understand it as a reference to the second day of Rosh Chodesh, while Rashi, and the Radak, say that it refers to the day after Rosh Chodesh, a regular day.
Some say that we observe two days because we are unsure which day is truly Rosh Chodesh. This opinion, however, has been rejected. Therefore, one who forgets to recite Ya’aleh VeYavo in Shacharit or Minchah, on either day, must repeat the Shemoneh Esrei. See Sefer Rosh Chodesh, ch. 10, note 4.
The Torah lists Rosh Chodesh together with all the other holidays on which we offer additional sacrifices (Musafim) in honor of the day’s sanctity. Chazal derive from a verse in Eichah(1:15) that Rosh Chodesh is also called mo’ed (an appointed time) like all the other holidays (Pesachim 77a). In Temple times, they used to blow trumpets on Rosh Chodesh, as it says, “On the day of your gladness, and on your appointed times, and on the beginnings of your months, you shall sound the trumpets over your burnt offerings and over the sacrifices of your peace offerings”(Bamidbar, 10:10).
Because of the sanctity of Rosh Chodesh, a custom developed to go out and greet one’s Rabbi, similar to the custom on the Sabbath to say “Shabbat Shalom” to the Rabbi of one’s shul. ( Melachim 2, 4:23, Rosh HaShanah 16b, Bi’ur Halachah 301:4). There is also a custom to prepare festive meals on Rosh Chodesh(cf. Shmuel 1, ch. 20).
A wonderful expression is used by the Torah when describing the goat that was sacrificed on Rosh Chodesh, calling it “a sin offering for the Lord”(Bamidbar, 28:15). The Talmud (Chulin 60b) explains that in the beginning, God created two great luminaries in the sky, the sun and the moon. The moon, however, made a claim to the Master of the World: “How can two kings share the same crown?” hoping that HaShem would diminish the sun so that it, the moon, could reign supreme. God, however, said to the moon, “Go and reduce yourself.” It replied, “Because I made a justified claim before You, I should reduce myself?” God consoled the moon by saying that the Jews would reckon the months according to its cycle, and that the righteous would be called by its name. But the moon was not consoled, so the Holy One Blessed Be He said, “Bring an atonement for Me, for I diminished the moon.” This is why it says, “And one kid of the goats for a sin offering for the Lord.“.
This contains a very profound concept. On a simple level, the moon’s reduction symbolizes the deficiencies that exist in creation, including the descent that the soul undergoes when it arrives in this world, and all the failures that man experiences during his lifetime. All these failures and deficiencies are prerequisites for subsequent growth, because coping with hardships helps one reach higher heights in the end, as R. Abahu says, “The purely righteous cannot stand where penitents stand” (Berachot 34b). In the meantime, people commit sins which cause great pain in the world. So, in order to relieve the pain and repair the flaws, HaKadosh Baruch Hu commanded us to sacrifice a goat as a sin offering. This is the purpose of Rosh Chodesh, to show us how a new beginning sprouts from the moon’s reduction, which happened as a result of sin and indictment. Therefore, Rosh Chodesh is a good time for repentance, new beginnings, and profound joy. However, until the world is redeemed from all its deficiencies, the joy of Rosh Chodesh is not completely revealed (see also below, sec. 15-16).
 A goat was brought as a sin offering on all the holidays, but no where else does it say, “a sin offering for the Lord.” The other musaf (additional) sacrifices offered on Rosh Chodesh were two bullocks, one ram, and seven sheep as a wholly-burnt offering (Bamidbar, 28:11).
Rosh Chodesh is among the holidays on which it is appropriate to rejoice. However, there is no explicit commandment to rejoice on Rosh Chodesh by partaking in festive meals. While it is meritorious to have special meals on the day, one is not obligated to do so (Shulchan Aruch, Orach Chaim 419:1).
Nevertheless, it is forbidden to grieve on Rosh Chodesh, and one may not fast on the day (ibid. 418:1). Anyone who refrains from eating on Rosh Chodesh, even for a short period of time, with intention to fast, commits a transgression. But if, by chance, one did not manage to eat for several hours, this is not considered a fast (Bi’ur Halachah 418, s.v. assur; Kaf HaChaim 3). According to the letter of the law, a person who ate only fruits on Rosh Chodesh is not considered as one who has fasted and transgressed a prohibition; rather, he simply failed to fulfill the mitzvah of enjoying festive meals on the day.
The main way to fulfill this mitzvah is by adding a special dish to one’s regular menu in honor of Rosh Chodesh,. even when Rosh Chodesh coincides with Shabbat(Mishna Berura 418:2, 419:1-2).
Even though one is not obligated to eat bread at a Rosh Chodesh meal, it is a mitzvah to do so (Sha’ar HaTziyun 419:1).
It is proper to set the table respectfully for a Rosh Chodesh meal. Some are meticulous about eating meat and drinking wine to celebrate the occasion.
When Rosh Chodesh lasts two days, there is a mitzvah to prepare festive meals on both days. This mitzvah is fulfilled mainly during the day, but some say that there is a mitzvah to eat larger meals at night, as well.
One is forbidden to do things on Rosh Chodesh that evoke sorrow. Therefore, eulogies are forbidden on Rosh Chodesh. If, however, the deceased was a Torah scholar, we eulogize him, but only if the body is present (Shulchan Aruch, Orach Chaim 420:1, with Mishna Berura; Yoreh De’ah 401:5).
Similarly, the custom is not to visit cemeteries on Rosh Chodesh. Therefore, if the anniversary of death (yahrtzeit) or the end of sheloshim (the first thirty days after death) coincides with Rosh Chodesh, the friends and relatives of the deceased should visit the grave on the day before Rosh Chodesh. And if that is impossible, they should go after Rosh Chodesh. One is permitted to visit graves of righteous Tzaddikim on Rosh Chodesh because this does not evoke sorrow.
A bride and groom who follow the custom of fasting on their wedding day (Ashkenazim and some Sefardim) should not fast if their wedding takes place on Rosh Chodesh(Shulchan Aruch 573:1).
Rashi states in Ta’anit (15b), “Even though it is called a mo’ed (appointed festival), [the Torah] does not call it a day of feasting and joy.” The Rosh (Berachot 7:23) concurs, stating that we do not insert the word simchah (joy) into the corrective blessing for Grace After Meals on Rosh Chodesh (see below note 14). In contrast, the author of Sefer Yirei’im (227) writes, “One is obligated to rejoice on Rosh Chodesh,” albeit one is not obligated to eat bread at the meal, because one can satisfy the requirement of joy by eating meat and drinking wine. The final halachah remains as stated above.
The Rambam holds that the prohibition of fasting on Rosh Chodesh is derived from the Torah, while the Beit Yosef (418) maintains that it is a Rabbinic decree. Pious individuals have a custom to fast on two specific Rosh Chodesh days –the first of Nisan, when Aharon’s sons were stricken, and the first of Av, when Aharon died (Shulchan Aruch 580:2). The Rama comments (ibid. 580:1) that one should not fast an entire Rosh Chodesh, rather he should eat before the stars emerge. A regular person should not accept upon himself to fast on these days of Rosh Chodesh. See Sefer Rosh Chodesh 14:13-14.
 The custom to embellish the mitzvah by setting the table respectfully is cited in Ben Ish Chai (Shanah bet, VaYikra 10) and Kaf HaChaim (419:5). Eating meat and drinking wine is also an embellishment in honor of Rosh Chodesh. According to Sefer Yirei’im, however, it is an actual mitzvah, as mentioned in the previous note. This is why most Sefardic Jews refrain from eating meat and drinking wine only from the second day of the month of Av, in order to uphold the honor of Rosh Chodesh. The Ashkenazi custom is to refrain from meat and wine on Rosh Chodesh Av, as well (see below 8:13). Also see Sefer Rosh Chodesh, ch. 12.
The Mishna Berura (419:2) writes that there is no need to have a festive meal on Rosh Chodesh night, but the Rama of Panow (79), and the Eshel Avraham of Buchach, maintain that there is a mitzvah to do so.
 According to the Rama (573:1) and the Mishna Berura (ibid. 9), they should fast on Rosh Chodesh Nisan, because the pious have a custom to fast on that day. The Pri Megadim maintains that one who does not usually fast on Rosh Chodesh Nisan should not do so on his or her wedding day. See Sefer Rosh Chodesh 14:19. In footnote 39 (ibid.), the author discusses the case of a wedding that takes place on the [first] night of Rosh Chodesh [when the bride and groom surely fast during the day prior to the wedding]. He explains that according to the Aruch HaShulchan (Even HaEzer 61:21), who holds that brides and grooms fast in order to ensure that they are not drunk at their wedding, they should continue fasting until after the chuppah, even though this will mean that they are entering Rosh Chodesh in an afflicted state. The Kitzur Shulchan Aruch (146:1), on the other hand, maintains that brides and grooms always fast only until nightfall, because the purpose of the fast is to procure atonement.
For more on visiting graves, see Yalkut Yosef 418:6-7, P’nei Baruch 37:10, and Sefer Rosh Chodesh 14:24.
It is permissible to do work on Rosh Chodesh. Ideally, though, one should not work on Rosh Chodesh, similar to the law regarding Chol HaMo’ed. The holier the day, the more it is designated for spiritual endeavors, and the more one should refrain from working. Thus, all work is forbidden on Shabbat, because it is the holiest day. Work is also forbidden on Yom Tov, a level below Shabbat, but one is permitted to do things necessary for the preparation of food. Chol HaMo’ed is the following level, when only certain acts are forbidden. Rosh Chodesh should rightfully be on par with Chol HaMo’ed, but since the Twelve Tribes sinned in the episode of the Golden Calf, Israel lost, correspondingly, the special quality of the twelve Roshei Chodeshim of the year. Women, however, did not participate in the sin of the Calf, refusing to contribute their nose-rings towards its creation. Therefore, God gave them reward in this world – “They keep Rosh Chodesh more than the men do” – and in the World to Come, for they will eventually regain their youthfulness, like the moon which renews itself every month, as it says, “Who satisfies your ornament with goodness, so that your youth is renewed like the eagle” (Tehillim 103:5. SeePirkei DeRebbe Eliezer 45). As a result, women experience more of the sanctity of Rosh Chodesh; and they have adopted the custom not to do work on the day. .
When the Temple stood and the kohanim offered Musaf sacrifices, some men also had the custom to refrain from doing major work on Rosh Chodesh. But their custom has no binding force, because men committed the sin of the Calf. Women, on the other hand, who did not sin, have more of a connection to the sanctity of Rosh Chodesh and their custom has validity.
Therefore, every woman must refrain from doing some type of work on Rosh Chodesh – knitting, for example – in order to differentiate between Rosh Chodesh and an ordinary day. It goes without saying that she may not plan to do any big jobs on Rosh Chodesh.
Meticulous women refrain from doing any type of work that is forbidden on Chol HaMo’ed. This includes sewing, knitting, and fixing things in the house. Cooking, baking, and ironing, however, are permitted, as they are on Chol HaMo’ed. Washing clothing in a washing machine is also permitted, because it entails almost no effort. If the clothes are needed for Rosh Chodesh itself, one may wash them even by hand. A woman who works for a living is permitted to do so on Rosh Chodesh, even if she generally adopts the customs of the meticulous, for if she misses work regularly on Rosh Chodesh, she might lose her job. And even if there is no concern of being fired, she may go to work if she needs the money, or if her absence will cause damage to her employer.
 This is how Pirkei DeRebbe Eliezer (45), the Tur (Orach Chayim 417), the Perishah (ibid. 1), and the Darkei Moshe (ibid. 1), quoting the Or Zaru’a, explain the issue. See Sefer Rosh Chodesh, beginning of ch. 11, where the author recounts all the reasons given for this matter. R. Chayim Vital explains in Sha’ar HaKavanot (76b) that women correspond to [the sefirah of] Malchut (Kingship) and the moon, which renew themselves, while men correspond to Tiferet (Splendor), which does not. Furthermore, Malchut undergoes a decline, from which it can reach even higher than Tiferet. A hint for this is “A virtuous woman is the crown of her husband” (Mishle, 12:4).
 The Tur and Beit Yosef (Orach Chaim 417) explain that the main source for this custom is a Yerushalmi (Ta’anit 1:6): “Those women who are accustomed not to work on Rosh Chodesh – it is a custom.” According to Rabbeinu Yerucham, a woman who never had such a custom need not take it on. However, the Bi’ur Halachah (417, s.v. ve’hanashim) writes that most Rishonim hold that all women must keep this custom, but they can satisfy their obligation by refraining from some type of work. If, however, they have a more stringent custom, forbidding additional types of work, their custom is binding. Indeed, there are those who act more stringently, and I referred to them as “meticulous ones.” The Eshel Avraham of Buchach says that even the meticulous ones should not treat Rosh Chodesh more stringently than they do Chol HaMo’ed. Therefore, washing clothes for the sake of Rosh Chodesh is permitted, because the reason for the prohibition on Chol HaMo’ed is only to ensure that people wash their clothes in anticipation of the holiday. Regarding washing machines: Sefer Rosh Chodesh(11:7) writes that there are those who are stringent, but that R. Shlomo Zalman Orbach permits it, because it involves no effort.The Aruch HaShulchan (417:10) writes that a woman is allowed to work on Rosh Chodesh in order to make a living, and that such is the prevalent custom. The author of Hilchot Chagim (1:5) agrees. This can be derived from a kal va’chomer (a fortiori): If she is liable to lose her job, or if she needs that day’s wages desperately, she is permitted to work even on Chol HaMo’ed, all the more so on Rosh Chodesh. If she can easily forgo working that day, then the meticulous ones act stringently. It seems to me that even meticulous women act leniently when it comes to writing for other than work-related purposes [even though this is generally prohibited on Chol HaMo’ed].
According to the Shibolei HaLeket, when Rosh Chodesh is two days long, the custom for women not to work applies only on the second day, which is the first of the new month. The Roke’ach holds that it applies both days. The author of Mor U’Ketziah maintains that the custom takes effect only during the day of Rosh Chodesh, not at night. It seems to me that women keep this custom at night, as well. See Mishna Berura (417:4), Bi’ur Halachah (end of 417), and Sefer Rosh Chodesh (11:8-9).
The Bi’ur Halachah (417, s.v. minhag tov) writes in the name of the Bach that a husband may not demand that his wife work on Rosh Chodesh, but she is permitted to do work if she pleases. As stated above, most poskim agree that a woman should, in any event, refrain from some form of work. Clearly, since a woman has a mitzvah to refrain from work, even though it is not obligatory, her husband cannot demand that she do work on Rosh Chodesh, except housework, like cooking.
The Chida, in Yosef Ometz (20), cites Rishonim who hold that men, as well, had a custom not to work on Rosh Chodesh, and he explains that this custom developed because they used to bow before God in the Holy Temple. The Turei Even (on Tractate Megillah) claims that the custom was based on the musaf sacrifices that were offered in the Temple on Rosh Chodesh. Either way, most poskim believe that this custom has no binding force, as the Mishna Berura writes in 417:2.
On the Shabbat before Rosh Chodesh, the custom is to announce the day or days on which the new month will fall, and to pray that “HaKadosh Baruch Hu renew it for us and all of Israel for goodness and blessing.” In a certain way, this also commemorates the sanctification of the new moon that the Beit Din used to perform. Therefore, the custom is to announce the exact time at which the new moon will appear (the molad). This is also why we stand during the ceremony, because the people used to stand before the Beit Din when it performed the mitzvah of Kiddush HaChodesh. There is only one Rosh Chodesh before which we do not bless the new month – Tishrei, because Rosh Chodesh Tishrei is also the holiday of Rosh HaShanah, and everyone knows that it’s coming.
We announce the coming of the new month specifically on Shabbat because that is when the entire congregation is gathered in the synagogue, and everyone will hear when Rosh Chodesh is slated to fall. Furthermore, all the days of the week receive blessing from Shabbat, and even the sanctity of Rosh Chodesh flows from the Shabbat that precedes it. Therefore, we bless the new month on that day. This is why we begin to feel on that Shabbat the festiveness of the forthcoming Rosh Chodesh.
Mishna Berura 417:1; Igrot Moshe, Orach Chaim 1:142; Sefer Rosh Chodesh 1:1-9. In notes 4-8 [of the last source], the author quotes the Yera’im, the Shibolei HaLeket, and the Or Zaru’a who say that the reason for Birkat HaChodesh is in order to let people know when Rosh Chodesh will be. The Ra’avyah writes that it is in commemoration of the Kiddush HaChodesh ceremony. For this reason, some communities give the Rabbi the honor of blessing the new moon (Sefer Rosh Chodesh 1:7). What I wrote concerning Tishrei is found in Sha’ar HaTziyun 417:2. For alternative reasons, see Sefer Rosh Chodesh 1:25. Some communities do not bless the month of Av, because of the calamities that occurred during that month, but the prevalent custom is to bless it. So explains Rav Kook, in Olat Re’iyah, vol. 2, p. 121, and Sefer Rosh Chodesh 1:27.
 This is why Ashkenazim refrain from saying memorial prayers for the dead on Shabbat Mevarchim (Rama, Orach Chaim 284:7, Mishna Berura 284:17). They even omit the Av HaRachamim prayer, which is said in memory of those killed in sanctification of God’s name [during the Crusades]. The only exceptions are the two Sabbaths prior to Rosh ChodeshIyar and Sivan, because the holy martyrs were killed [mainly] during these two months. My teacher and rabbi, Rav Tzvi Yehudah HaKohen Kook, used to recite Av HaRachamim even on [an ordinary] Shabbat Mevarchim. He held that after the Holocaust it should be said on every Shabbat, just like it is said before Rosh ChodeshIyar and Sivan.
Rosh Chodesh is a time of atonement, as we say in the Musaf prayer, “A time of atonement for all [the Jewish people’s] offspring.” In addition, when the Temple stood, a he-goat would be sacrificed as a sin offering.
In order to make this atonement complete, pious Jews customarily repent in preparation for Rosh Chodesh. Some people fast on the eve of Rosh Chodesh and recite special “Yom Kippur Katan” prayers prior to the Mincha service. The day before Rosh Chodesh is called “Yom Kippur Katan” ( Minor Day of Atonement) because it is a time to atone for the sins of the previous month, just as Yom Kippur is a time to atone for the sins of the previous year (see Mishna Berura 417:4, Kaf HaChaim 10-21). Nowadays, few people follow the custom of fasting; instead, one should study more Torah and give extra charity.
The unique nature of Rosh Chodesh finds expression in our prayers. After all, Chazal instituted our prayers in place of the sacrifices, and the Torah commands us to offer a musaf sacrifice on Rosh Chodesh. Therefore, the Rabbis prescribed that we recite the Ya’aleh VeYavo prayer, in which we beseech God to remember us for good on Rosh Chodesh. They inserted it in the blessing of “Retzeh” because that is where we ask God to restore the Divine service to the Holy Temple, and that is an appropriate place to mention Rosh Chodesh, for once the Divine service is restored, we will be able to actually offer the musaf of Rosh Chodesh. One who forgets to say Ya’aleh VeYavo in Shacharit or Mincha must repeat the Shemoneh Esrei(Shabbat 24a).
If one remembers immediately after completing the blessing of Retzeh, he should insert Ya’aleh VeYavo there, and then continue with Modim. If one already began Modim, but remembered before moving his feet back at the end of Shemoneh Esrei, he should return to the beginning of Retzeh and continue from there until the end. The preceding is true only regarding Shacharit and Mincha, but if one forgot to say Ya’aleh VeYavo in Ma’ariv, he does not go back, unless he remembers before saying God’s name at the conclusion of Retzeh. The reason Ma’ariv is different is that the Beit Din did not sanctify the new moon at night. Thus, even though one should, ideally, say Ya’aleh VeYavo in Ma’ariv, he does not repeat the Shemoneh Esrei, or even just one blessing, in order to say it (Berachot 29b, 30b; Shulchan Aruch, Orach Chaim 422:1).
 If one is unsure whether or not he said Ya’aleh VeYavo in Shacharit or Mincha, he probably did not, and he must pray again. However, if he had in mind, in the middle of his prayers, to add Ya’aleh VeYavo, but a doubt arose later on as to whether or not he actually did so, he can assume that he said it, and he need not pray again (Mishna Berura 422:10). One who forgot to say Ya’aleh VeYavo in the final Mincha service of Rosh Chodesh should recite Shemoneh Esrei twice in Ma’ariv, stipulating that if he is not obligated to pray twice his second prayer should be considered a voluntary one (Shulchan Aruch 108:11; Peninei Halachah on Prayer, 18:10).
Customarily, the gabbai (sexton) calls out, “Rosh Chodesh” or “Ya’aleh VeYavo” prior to the Silent Prayer of Ma’ariv (Shulchan Aruch 236:2). In Shacharit, however, one may not interrupt between the blessing of Geulah (Redemption) and the Silent Prayer. Therefore, the custom is to bang on the podium twice, and the congregants understand this to be a reminder to insert Ya’aleh VeYavo. In addition, some have a custom to raise their voices a bit when they reach the words Ya’aleh VeYavo in their private prayers to remind others to say it (Shiyurei Knesset HaGedolah). See Sefer Rosh Chodesh 4:2. Another suggestion is for the leader to end the blessing of Ga’al Yisrael in a Rosh-Chodesh tune, in order to remind the people to say Ya’aleh VeYavo.
There is a widespread custom to recite Hallel on Rosh Chodesh. Indeed, according to the letter of the law, there is no obligation to do so, because Hallel is required only on days that are called mo’ed (appointed times), and when work is prohibited. Rosh Chodesh is called a mo’ed, but work is permitted on the day. Still, the Jewish people have accepted the practice of saying Hallel on Rosh Chodesh, in order to give expression to the sanctity of the day, which is capable of elevating one to the level of singing God’s praises. To make it clear that the Hallel of Rosh Chodesh is based on custom, and not obligatory, we omit two paragraphs that are said when reciting the complete Hallel (the complete Hallel consists of chapters 113-118 of Tehillim, and we skip 115:1-11 and 116:1-11).
The Rishonim argue about the blessing. The Rambam and Rashi hold that no blessing is said over the Rosh Chodesh Hallel, since it is only based on a custom, and we do not recite blessings upon the fulfillment of customs. Rabbeinu Tam, the Rosh, and the Ran, however, maintain that we do make blessings over important customs, such as reciting the Hallel. In practice, the Ashkenazi custom is to recite a blessing, even if one says the Hallel in private. The Sefardim who come from Eretz Yisrael and its surroundings never say a blessing on this Hallel. The custom of most North African Sefardim is that the cantor recites the blessing – both before and after Hallel – aloud, in order to absolve the congregation of their obligation. But one who prays alone does not recite a blessing. Each person should continue to follow his custom.
One should try to say Hallel with a minyan. According to many poskim, one who comes late to services and finds the congregation saying Hallel should say it with them, and only afterwards begin Pesukei DeZimrah(Mishna Berura 422:16 and Yalkut Yosef 422:8; the Kaf HaChaim [422:38], however, cites the Ari as saying that one should not pray out of order).
 The issue of Hallel on Rosh Chodesh is elucidated in Arachin 10b, Ta’anit 28b, Tosafot ibid., and TosafotBerachot 14a. See Sefer Rosh Chodesh, chap. 6, sections 1-6 and 20, with notes. Notes 2 and 27, there, explain the reason for the custom. There is another type of obligatory Hallel, which is not dependent on the sanctity of a day, rather on a salvation, like the one said on Chanukah. See below 4:6 and 11:8.
Practically speaking, most Rishonim hold that one should say a blessing on this Hallel, including Behag, Ritz Giat, Ra’avad, Rabbeinu Tam, Rosh, and Ran. Rav Hai Gaon, Rabbeinu Chananel, and Talmidei Rabbeinu Yonah maintain that one recites a blessing when saying it in public, but not in private. See Beit Yosef and Shulchan Aruch 422:2. Indeed, as the Shulchan Aruch writes, the Jews living around Eretz Yisrael were accustomed to saying it without a blessing, but the Jews of Spain recited the blessing (Ran, Maggid Mishna). The Rama (422:2) writes that the custom is to say a blessing, even when reciting Hallel alone, but that it is preferable to say it with a minyan, in order to satisfy those [authorities] who hold that one says the blessing only in public.
Until recently, several Sefardic communities, like Morocco, Tunisia, and Turkey, followed the custom in which the cantor says the blessings – before and after Hallel – aloud, and the congregation answers, “Amen,” thus discharging their obligation; while those who pray privately omit the blessings. In his Tevu’ot Shemesh (Orach Chaim 68), RavMashash determined this to be the practical halachah, and he himself would recite the blessing in an undertone, along with the cantor. This is also the opinion of R. Moshe Kalfon HaKohen, av Beit Din of Djerba, in Brit Kehunah (Orach Chaim 200:5); Sho’el VeNish’al (2:60); R. Chayim Palagi in Kaf HaChaim (end of 33); the authors of Shalmei Chagigah (p. 224); Chesed LeAlafim (422:2); Sha’ar HaMefa’ked; and Responsa Mikveh HaMayim (3:24). Every community should continue following its own custom.
When people from various ethnic groups pray together, even if the cantor’s custom is to skip the blessing, it is proper for one of the participants, who usually says a blessing, to say the blessing out loud and have in mind to absolve those who do not say a blessing of their obligation. This way, the congregants will satisfy the opinion of the many poskim who hold that one is required to say a blessing, and at the same time avoid the concern of making a blessing in vain. (See Yechaveh Da’at 4:31, where the author is apprehensive about answering “Amen” to this blessing, for it may be in vain. However, many authorities hold that one need not worry about answering “Amen” to someone who makes a blessing in accordance with his ancestors’ custom, which is based on the viewpoint of prominent poskim. I also heard this from HaRavHaGaon Mordechai Eliyahu, of blessed memory.)
According to all opinions, one should try to say Hallel with a congregation. Hence, it is better to say it with a minyan before prayers than to say it alone afterwards. This is the opinion of Rabbeinu Peretz, as cited in the Beit Yosef (422:2). Many Acharonim quote this as well, as we stated above, and as the author of Sefer Rosh Chodesh writes (chap. 23, n. 44). According to the Kaf HaChaim (422:38), one should not change the order of the prayers.
One must say Ya’aleh VeYavo in Birkat HaMazone (Grace after Meals), as well. Even though one is not obligated to eat a meal on Rosh Chodesh, one must mention it when reciting Birkat HaMazone because of the importance of the day, which requires additional sacrifices (Shabbat 24a with Tosafot). Ya’aleh VeYavo is inserted in the blessing of Rachem, because both are prayers of supplication.
If one forgot to say Ya’aleh VeYavo in Birkat HaMazone, he need not repeat the prayer because one who forgets to mention the sanctity of a particular day must repeat Birkat HaMazone only on days when there is an obligation to eat a meal with bread, like Shabbat and Yom Tov. On Rosh Chodesh and Chol HaMoed, however, one is not obligated to eat such a meal. Therefore, from the perspective of the sanctity of the day, one need not recite Birkat HaMazone. Consequently, if one accidentally omitted Ya’aleh VaYavo, he need not repeat it. (Shulchan Aruch 424:1).
One who began a meal on Rosh Chodesh, and managed to eat a kezayit (olive-size) of bread before sunset, must say Ya’aleh VeYavo in Birkat HaMazone, even if he continued eating long after nightfall (“when the stars emerge”), because the meal began on Rosh Chodesh(Shulchan Aruch 188:10; some argue, see Kaf HaChaim 43).
If one began to eat on the eve of Rosh Chodesh, and finished his meal after nightfall, he must say Ya’aleh VeYavo, provided that he ate a kezayit of bread after Rosh Chodesh began (Shulchan Aruch 271:6, Mishna Berura 29).
 If one realizes that he forgot Ya’aleh VeYavo before beginning the blessing of HaTov VeHaMeitiv, our Sages decreed that he should say, “Blessed are You, Lord our God, King of the Universe Who gave New Moons to His people Israel as a remembrance” (Shulchan Aruch 188:7). According to the Bi’ur Halachah, one should say God’s Name and mention His Kingship when reciting this blessing, just as one does on Shabbat and Yom Tov. The Kaf HaChaim (31), however, maintains that God’s Name and Kingship are omitted.
 If one did not eat a kezayit of bread after the stars emerged, the Shulchan Aruch rules that he must, nonetheless, say Ya’aleh VeYavo, as is the law on Shabbat, as explained there. According to the Rama, however, he should not say it. The Acharonim also dispute the case of one who began Seudah Shlishit on Shabbat and finished his meal on Saturday night, which is the beginning of Rosh Chodesh. See Peninei Halachah, Shabbat, 6:3, note 5, p. 99.
One must stand while reciting the Hallel, because Hallel is a testimony to God’s glory, and witnesses must stand while testifying. After the fact, if one said Hallel sitting or lying down, he has nonetheless fulfilled his obligation. Someone who is ill and cannot stand may say it sitting or lying down from the outset (Shulchan Aruch 422:7, Mishna Berura 28).
One should not interrupt the recitation of Hallel, even by just remaining silent. In the case of a pressing need, however, like preventing an insult, one may interrupt. One may also interrupt Hallel in order to recite “holy responses” [like Kedushah, Kaddish, and Barachu]. One should say Hallel in order, from beginning to end. One who said it out of order has not fulfilled his obligation and must go back to the place where he erred and read it in its proper sequence (Shulchan Aruch 422:4-6). It is proper to read Hallel slowly and pleasantly, and many congregations have a custom to sing portions of the verses.
Our Sages ordained that Hallel be said immediately after Shacharit prayers After all, we mention the uniqueness of Rosh Chodesh in the Silent Prayer, by saying Ya’aleh VeYavo. Therefore, it is appropriate to [immediately] continue praising God and thanking Him for sanctifying the Jewish people and the New Moons. Under extenuating circumstances, one may say it later in the day, because, according to the letter of the law, the entire day is suitable for the reading of Hallel(Megillah 20b).
There are various customs surrounding the Hallel’s recital, regarding which verses are repeated twice, and which verses are said responsively, etc. All the customs are proper, and every community should continue following its custom (Sukkah 38a-39a; Shulchan Aruch 422:3).
Customarily, the cantor reads four verses aloud (Tehillim, 118:1-4): 1) הודו לה’ כי טוב כי לעולם חסדו – Give thanks to the Lord for He is good, for His kindness endures forever. 2) יאמר נא ישראל כי לעולם חסדו – Let Israel say now, “For His kindness endures forever.” 3) יאמרו נא בית אהרן כי לעולם חסדו – Let the House of Aharon say now, “For His kindness endures forever.” 4) יאמרו נא יראי ה’ כי לעולם חסדו – Let those who fear the Lord say now, “For His kindness endures forever.” According to Ashkenazi custom, the congregation responds,הודו לה’ כי טוב כי לעולם חסדו to each of these verses. According to the Sefardic custom, however, the congregation repeats each verse after the cantor.
Regarding the duplication of verses, it has become the accepted custom, in the last few generations, to repeat all the verses from אודך until the end of Hallel(Tehillim, 118:21-29). The reason we say these verses twice is that the beginning of the chapter repeats every idea twice, but from אודך on, the verses cease repeating themselves. We, however, continue the pattern of the Psalm and double up the rest of the verses. Furthermore, King David, his father Yishai, and his brothers composed these verses, as the Talmud relates (Pesachim 119a). Thus, because of their importance, [Chazal] wanted us to say them twice.
We read the verse, אנא ה’ הושיעה נא, אנא ה’ הצליחה נא – “Please, O Lord, save us; Please, O Lord, make us successful”(Tehillim, 118:25), in a special way, saying the first part twice, and then the second part twice.
Rav Amram Gaon mentions both customs in his siddur, the first one as the Sefardic custom, and the second as the Ashkenazi practice. Tosafot and the Ran (Sukkah 38b) also cite the Ashkenazi custom [as described above], as do the Tur and Beit Yosef 422:3. The congregation fulfills their obligation to say [the other three verses] by hearing the cantor chant them out loud. Therefore, they can simply answer הודו לה’ כי טוב כי לעולם חסדו. Many Acharonim write that since there is reason for concern that some congregants may not hear the cantor properly, it is best for the congregation to say the verses along with the cantor, finish shortly before him, and then answer הודו לה’ כי טוב כי לעולם חסדו. This is the opinion of Magen Avraham 422:8, Eliyah Rabbah 13, Machatzit HaShekel and Mishna Berura 20. See also Sefer Rosh Chodesh 6:15.
 According to Sefardic tradition, the cantor, followed by the congregation, says the first part twice and then the second part twice. The Ashkenazi custom is that the cantor and the congregation say each verse responsively. This raises a question. The Talmud states in Megillah 22a that one is forbidden to interrupt a verse in the middle, except for the purpose of teaching young children. Tosafot (Sukkah 38b) answer that two people composed this verse – David and his brother. The Kolbo suggests that one is forbidden to split a verse in two only if it is from the Torah (Magen Avraham 422:8). The Maharsham explains in Da’at Torah that one is permitted to divide a verse if it is being used for prayer. See Sefer Rosh Chodesh 6:18, n. 37.
Ashkenazim say the four verses beginning with the words אודך, אבן מאסו, מאת ה’, זה היום twice. The custom of many Jews from North Africa is that the cantor says each verse once, after which the congregation responds likewise, and since “hearing is like answering,” it is considered as if they said each verse twice.
In honor of Rosh Chodesh we call up four people to the Torah. The reading begins with the daily burnt offering and ends with the special Rosh Chodesh sacrifices (Bamidbar, 28:1-15). This hints to the fact that the special sanctity of Rosh Chodesh, which incorporates renewal, atonement, and repentance, stemmed from the fixed and continual sanctity that manifests itself in the daily burnt offering, which was sacrificed every morning and afternoon.
After the Torah reading and the recitation of Ashrei and U’Va LeTzion (and according to some Sefardim, Beit Ya’akov and the daily Psalm, as well), we say the Silent Prayer of Musaf. This prayer is comprised of the usual three opening and closing blessings, with one middle blessing about Rosh Chodesh, which concludes, “Blessed are You, HaShem, Who sanctifies Israel and the beginnings of the months.”
Our Sages instituted the Musaf service in place of the additional musaf sacrifices that were offered in the Beit HaMikdash on Rosh Chodesh. The time frame for saying this prayer also corresponds to that of the additional sacrifices. Thus, one must pray Musaf by the end of the seventh hour of the day, calculating each “hour” as one-twelfth of daylight. One who procrastinates and fails to pray by this time is considered a sinner. Nevertheless, he should pray afterwards, because, b’dieved (ex post facto), one may offer the additional sacrifices all day long (Shulchan Aruch 286:1).
The custom is to remove one’s tefillin before the Musaf prayer. On Yom Tov (major Jewish holidays) we do not wear tefillin at all. Since the day itself is a “sign” (ot) between God and Israel, we do not need the additional “sign” of tefillin. Similarly, the Musaf prayer on Rosh Chodesh is considered a “sign,” and we do not need the additional “sign” of tefillin(Shulchan Aruch 423:4, Mishna Berura 10). The custom is to remove them after the Kaddish that precedes Musaf. It is proper to start praying only after the tefillin are completely wrapped in their straps and stored away in their bags. Otherwise, they will lie there throughout the Musaf service, without receiving the respect demanded by their great holiness.
Another prevalent custom is to say the Psalm beginning with Borchi Nafshi(Tehillim 104) during Shacharit, because it contains the verse, “He made the moon for appointed festivals.” Some believe that the Levites recited this Psalm in the Beit HaMikdash on Rosh Chodesh(Aruch HaShulchan 423:5).
 The Beit Yosef (25:13) gives a different reason, stating that it is inappropriate to be without the crown of tefillin when saying the stanza beginning with Keter (“crown”) in the Kedushah of Musaf. However, even Ashkenazim, who omit Keter, are accustomed to removing their tefillin before Musaf. Therefore, I cited the Levush’s explanation that Musaf is considered a “sign,” similar to Yom Tov, on which we do not wear tefillin (Shulchan Aruch, Orach Chaim 31:1). See Sefer Rosh Chodesh 8:1. The prevalent custom is to remove the tefillin after Kaddish (according to the Ba’al HaTanya’s siddur, they are removed before Kaddish). See Sefer Rosh Chodesh 8:4-6.
This raises a question regarding the common practice to don tefillin at the circumcision of one’s son, in order to be surrounded by two signs, the sign of the brit and tefillin. Do we not learn from the law of tefillin on Shabbat and Yom Tov that one should not display two signs together, for each one implies that the other is insufficient, thus degrading its significance (Shulchan Aruch 31:1)? The Eliyah Rabbah (29) answers in the name of the Roke’ach that the sign of circumcision is not in commemoration of the Exodus from Egypt; therefore, it is good to combine it with another sign that is. Tefillin, Shabbat, and Yom Tov, however, are in commemoration of the Exodus and should not be joined together.
 For the order of the Torah reading, see Tur, Beit Yosef, Shulchan Aruch, and Mishna Berura 423:2; Yalkut Yosef 423:4; Sefer Rosh Chodesh 7:9. If one said Musaf before Shacharit, he has discharged his obligation, but ideally one must pray Shacharit first, just as one must sacrifice the daily burnt offering before all other offerings (Rama 286:1).
For more on Borchi Nafshi, see Sefer Rosh Chodesh 7:5. The following authorities hold that Borchi Nafshi was the daily song for Rosh Chodesh in the Temple: The Vilna Gaon (Ma’aseh Rav 157), B’nei Yissachar (Rosh Chodesh 3:1), and Aruch HaShulchan (423:5, 424:3). Ashkenazim and Chassidim (Nusach Sefard) say Borchi Nafshi after the regular daily song; the Chassidim recite both songs after Hallel; and the Ashkenazim after Musaf (Sefer Rosh Chodesh 7, n. 5). Some Sefardim have the custom of saying the daily song after U’Va LeTzion, before the Kaddish that precedes Musaf, and Borchi Nafshi after Musaf. Others say Borchi Nafshi after Musaf and omit the daily song altogether.
The Ashkenazim customarily return the Torah scroll to the Ark immediately after it is read (Mishna Berura 423:5). The Shulchan Aruch (423:3) writes that it should be returned after U’Va LeTzion, and Sefardim and Chassidim follow this practice. (However, the author of Kaf HaChaim [135:2 and 423:11] agrees with the Ashkenazi custom, and Rav Ovadyah Yosef follows it for Kabbalistic reasons, returning the Torah scroll, on Rosh Chodesh and Mondays and Thursdays, immediately after the reading [Yalkut Yosef 423:6 with notes].)
In the Blessing of the Moon (Birkat HaLevanah), we thank Hashem for creating the moon, and for the benefit we receive from its light. Many attach special honor to this blessing, because it alludes to deep concepts concerning the Jewish people. We will explain some of these ideas:
Of all the heavenly bodies, the moon is most similar to us. Just as a person’s life is filled with ups and downs, so too, the moon waxes and wanes. In the middle of the month, it looks full, but as it nears the end of the month it dwindles and disappears. And just as Adam paid dearly for giving in to his pride and desires when he ate from the Tree of Knowledge , so too, the moon was not satisfied with being originally the same size as the sun, wanting instead to rule over it (see above, sec. 5). In retribution for the moon’s arrogance, HaKadosh Baruch Hu reduced its light and created the lunar cycle in which its light decreases every month, eventually disappearing from the sky. However, unlike man, who fades away and dies, the moon is part of the heavenly hosts and is fixed and everlasting, always regenerating itself. The Jewish people have the exact same qualities. On the one hand, they lead normal human lives, which include ups and downs, with good inclinations as well as evil ones. Yet their connection to faith and God is everlasting. Therefore, unlike other nations, Am Yisrael endures forever. Thus we are reminded of Israel’s immortality in Birkat HaLevanah, when we see the moon reappear and grow stronger every month.
Moreover, not only do we manage to survive despite all the hardships, we actually advance to a higher level as a result of each crisis and setback. King David, whose kindom is compared to the moon, taught us how to transform each setback into an impetus for greater growth. Chazal tell us that David was the least esteemed of his brothers, growing up in the fields amongst the sheep, but he, matured and developed from every experience. Even after his difficult fall in the episode of Bat-Sheva, he didn’t give in to despair. Rather, he repented completely, to the point where Chazal say that “he established the yoke of repentance” (Mo’ed Kattan 16b). David transformed the regrettable incident into a catapult of tremendous self-improvement, setting an example for all generations. We learn from him the ways of repentance and its power of renewal. By virtue of his repentance, David’s kingdom is everlasting, just like the moon which always rejuvenates after its decline.
This is why we say in the Kiddush Levanah ceremony, “David, King of Israel, lives and endures.” Likewise, the Jewish people, as well, grow from every setback, rectifying all their sins and blemishes, until they will eventually be privileged to perfect the world through God’s sovereignty. At that time, the moon, which symbolizes our situation in the world, will also return to its perfected state, when its light will be as bright as the sun’s. Thus, we beseech God in Birkat HaLevanah, “It (the moon) should renew itself like a crown of glory for those borne from the womb (the people of Israel), who will eventually renew themselves like it and glorify their Maker for the sake of His glorious kingdom.”
Some have a custom to add the following request: “May it be Your will, Lord my God and God of my forefathers, to repair the moon’s defect, that there be no deficiency in it. Let the light of the moon be like the light of the sun and like the light of the seven days of Creation, as it was before it was reduced, as it says, ‘The two great luminaries’(Bereshit, 1:16). And may the following verse be fulfilled through us: ‘They shall seek the Lord their God and David their king’(Hoshea, 3:5). Amen.
 Numerous Midrashim indicate that the Gentiles follow the solar calendar, including the Christians. We can explain this as follows: The desire to utilize the sun stems from a desire for absolute perfection. However, that is beyond man’s reach. And since the Gentiles fail to attain absolute perfection, they forfeit what they could have achieved by revealing God’s Name in the world. The Jews, on the other hand, know how to operate within this world while clinging to God, which manifests itself through constant self-perfection. Calculating the months according to the moon’s cycle alludes to our efforts in this world, while calculating the years according to the sun’s orbit hints to our constant aspiration for perfection. The Muslims learned from the Jews to count by the moon, but only by the moon. This signifies a lack of aspiration for continuous self-perfection and an entrenchment in this world. It also explains why they perceive reward, even in the hereafter, in physical terms.
It is important to add that even when the moon is invisible to us, it remains whole in its “hiding-place.” It’s just that all the light it absorbs from the sun is reflected back towards the sun and is thus indiscernible on earth. The same is true of the Jewish nation: even when it descends, its inner essence remains unblemished, as it says, “You are entirely beautiful, my love, and there is no blemish in you” (Shir HaShirim 4:7).
Because of the exalted themes behind the moon’s renewal, the person who recites the Blessing of the Moon is considered as one who receives God’s Presence (the Shechinah). Thus, Tanna D’vei Rebbi Yishmael states, “Had the Jews been privileged to greet their Father in Heaven only once a month (when reciting Birkat HaLevanah), it would be sufficient” (Sanhedrin 42a). Therefore, Abaye concluded that one must honor the blessing and recite it while standing (ibid.). One who finds it difficult to stand should lean on his cane, or on a friend, and recite the blessing. If leaning is too difficult, he may say it while sitting.
The custom is to honor the blessing by saying it with a minyan. In the absence of a minyan, it is best to say it in a group of three, but according to the letter of the law one, may recite it alone. If one is concerned that waiting for a day on which a minyan can be gathered will cause him to forget to say the blessing altogether, it is preferable not to wait, and to say it alone (Biur Halachah 426:2, s.v. ella).
It is customary to leave the synagogue or one’s house and recite the blessing under the open sky. We learned above that Birkat HaLevanah is compared to greeting the Shechinah. Therefore, just as one goes out to greet a king, one should go out to recite this blessing. A person who is sick, or fearful that he might catch a cold if he ventures outside, may glance at the moon through a window and say the blessing indoors (Mishna Berura 426:21).
In order to honor the blessing, which contains an aspect of greeting the Shechinah, we are accustomed to recite it immediately after Shabbat, when we are joyful and nicely dressed . However, if there is reason to fear that waiting until Saturday night will cause us to miss the opportunity to say the blessing, it is preferable to say it on a weeknight (Shulchan Aruch, Rama 426:2).
The custom is not to recite Birkat HaLevanah on Friday night, in order to avoid mingling the joy of Shabbat with that of Birkat HaLevanah. However, if there is reason to fear that one will miss the blessing if he does not say it on Friday night, he should recite it then (Rama 426:2, Mishna Berura 12).
As we already learned, the moon alludes to Knesset Yisrael (the Assembly of Israel). Knesset Yisrael is like a bride before God, and “she” renews and purifies herself every month, just like a bride does for her husband. This strengthens the bond between Knesset Yisrael and HaKadosh Baruch Hu. And when all of the world’s flaws are remedied, everyone will recognize the special relationship that exists between Israel and the Holy One Blessed be He, as it says, “Like a bridegroom rejoices over a bride, so will your God rejoice over you” (Yeshayahu, 62:5). Therefore, a custom developed to dance and sing after Birkat HaLevanah, just as at a wedding. Along the same lines, there is a custom to raise up a bit when saying, “Just as I dance before You…” (Rama 426:2).
Since we must say the blessing joyously, we do not to recite it before Tish’a B’Av – because of our mourning over the Temple’s destruction – nor before Yom Kippur, due to our anxiety over the upcoming Day of Judgment. We do say it, however, immediately after Yom Kippur, even though we have not yet eaten, because we are joyous over having had the privilege to stand before God in penitence. It is proper to postpone Kiddush Levanah until the night after Tish’a B’Av, or until people have had a chance to eat and drink and leave their state of mourning (Rama 426:2). However, if it will be difficult to gather a minyan later on, a congregation may sanctify the moon immediately after the fast is over (Mishna Berura 426:11, Sha’ar HaTziyun 9; see also below 10:19).
Similarly, one who is sitting shiva should push off reciting the blessing until after the shiva, if possible, because he is grieving, even if he will have to say it alone. If, however, he cannot push it off – because shiva will end after the permissible time to say the blessing – he should say it during his mourning period (Mishna Berura 426:11, Kaf HaChaim 5. The latest time to recite the blessing will be elucidated below, sec. 18).
Shulchan Aruch 426:2; Rabbi Akiva Eiger, ibid.; Biur Halachah, end of s.v. u’mevarech me’umad; Yalkut Yosef 426:11. (The Ben Eish Chai – Shannah Bet, VaYikra 23 – writes that it is proper to recite the blessing with one’s feet together, but the prevalent custom is not to do so.)
Reciting this blessing is like greeting the Shechinah because the Shechinah alludes to Knesset Yisrael (the Assembly of Israel), both being a part of the attribute of Malchut (Kingship). See also the Maharal of Prague’s Chiddushei Aggadot, 3:158, which states that every initial renewal contains an aspect ofreceiving the Shechinah. The author of Biur Halachah (426:2, s.v. u’mevarech me’umad) writes that we recognize God’s greatness through the moon and stars; therefore, saying this blessing is similar to receiving the Shechinah.
We recite the blessing over the new moon at night, because that is when it is clearly visible and one can benefit from its light. One may not recite the blessing if he sees the moon at twilight, because the sun’s light is still shining and one does not benefit from the light of the moon at that time (Rama 426:1). Before reciting the blessing, one must look at the moon for a moment in order to derive pleasure from its light, but the custom is not to look at the moon when actually reciting the blessing (Mishna Berura 426:13, Kaf HaChaim 34). If one recites the blessing when the moon is covered by clouds he has not fulfilled his obligation, because he cannot benefit from its light. However, if it is covered only by a thin cloud, and one can see things that are usually visible by the light of the moon, he may say the blessing. Nevertheless, it is best to say the blessing when the moon is clearly visible, with no obstruction. Some authorities write that it is preferable to postpone Birkat HaLevanah when the moon is even slightly covered, but according to the letter of the law, one may recite the blessing even if a thin cloud passes over the moon, since one can derive benefit from its light. It seems to me that as long as one can discern the outline of the moon through the cloud, it is permissible to recite the blessing.
If, while reciting the blessing, the moon becomes completely covered by clouds, one should continue saying the blessing. However, if one estimates that while reciting the blessing a big cloud will come and cover the moon completely, he should not start the blessing, because ideally (l’chatchilah) the entire blessing must be said when the moon is in view (Ridbaz 1:346; Mishna Berura 426:2; Biur Halachah, s.v. nehenin).
 The Ridbaz (1:341) writes thatit primarily depends on the ability to derive benefit from its light, and many Acharonim cite his words, including the Magen Avraham and Mishna Berura 426:3. However, the Chida writes in Moreh BeEtzba (184) that one may not recite the blessing even if the moon is covered only by a very thin cloud, and the Ben Eish Chai (Shanah Bet, VaYikra 23) concurs. Nevertheless, according to the letter of the law, it seems that all agree that one may recite the blessing as long as one benefits from the light. This is the conclusion of the Yalkut Yosef 426:5.
The Eshel Avraham of Buchach explains that one may recite the blessing if the light of the moon allows one to see most of the things that are usually visible when the moon is unobstructed. This is assessed based on the moon’s light on the seventh night of the month, or the fourth of the month, if there is a pressing need. In his opinion, one may recite the blessing towards the middle of the month even if the moon is covered by a thicker cloud, and one may recite it towards the beginning of the month only if the cloud is very thin. The poskim, however, seem to indicate that the distinction depends on the thickness of the cloud, not the day on which the blessing is recited. So writes the author of Sefer Kiddush Levanah 2:3 (with notes). Therefore, in my humble opinion, it seems that if one can see the outline of the moon, it is considered “visible” (possibly even according to those who are meticulous), and the blessing may be said.
According to the letter of the law, though, the halachah follows the opinion of the Ridbaz and the Eshel Avraham. This is apparent from the words of the Terumat HaDeshen quoted in Leket Yosher: “Once, he saw only a small portion of the moon, because it was partially covered by a cloud, and he nevertheless sanctified [it].”
Some say that one should look at the moon only briefly. See Mishna Berura 426:13 and Kaf HaChaim 34.
Many authorities write that one who recited the blessing without looking at the moon has fulfilled his obligation, as long as he could have seen it had he looked (see Sefer Kiddush Levanah 2:11). They derive this by logical inference from [the law of] a blind man. Most poskim hold that a blind man must say Birkat HaLevanah, because the blessing was instituted in recognition of the renewal of the moon. In addition, even the blind benefit from the moon in that others use its light to escort them. This is the viewpoint of the Rashal, Magen Avraham, Eliyah Rabbah, and Pri Chadash. However, the Maharikash holds that a blind man should not recite the blessing, for he does not derive pleasure from the moon. In practice, a blind man should not recite the blessing, because of the uncertainty surrounding the matter. It is preferable for him to hear the blessing from someone else (see Mishna Berura 426:1; Biur Halachah, s.v. nehenin; Kaf HaChaim 2).
 See Sefer Kiddush Levanah (chap. 2, n. 9) where the author quotes Rav Pe’alim (vol. 3, Orach Chaim 68) who is unsure how to rule in a case where the moon will disappear in the middle of the blessing, but no days remain on which to recite Birkat HaLevanah. He concludes, “It is possible to say that under such dire circumstances everyone agrees that one should say the blessing, but further investigation is required.” The author of Halichot Shlomo (Tefillah 15:12) writes that if one is concerned that immediately after beginning the blessing, the moon will be covered, it is permissible to say the blessing, b’diavad.
Many Rishonim hold that the time for Birkat HaLevanah starts on the first day that the moon is visible, and that the earlier one says the blessing the better (Rambam, Hilchot Berachot 10:17; Rosh; and others). Several poskim, however, maintain that it is preferable to wait until the moon increases a bit, when it is possible to benefit from its light. Some say one should wait until three whole days pass, for that is when the moon’s light becomes substantial (R. Saadia Gaon, Talmidei Rabbeinu Yonah). Others say seven days must pass, because that is when one can truly benefit from its light (Rama of Panow, Responsa 78). According to some of the greatest Kabbalists – most notably, R. Yosef Gikitilla – one should wait seven days, for esoteric reasons. They explain that the renewal of the moon’s light alludes to man’s renewal, and whenever there is a new development, there is concern that the Attribute of Justice might prosecute and hinder the new growth. Therefore, it is proper to wait seven days, like the seven days of Creation, for by then the moon’s light has stabilized and the Attribute of Justice can no longer wage war against the new beginning.
Sefardim and Hasidim are accustomed not to recite the blessing before the seventh of the month (Shulchan Aruch 426:4), while Ashkenazim say it after three days (Bach, Mishna Berura 426:20). In practice, the custom is to bless the new moon on Saturday night, in order to say the blessing joyously, while wearing nice clothing. Thus, practically speaking, Ashkenazim and Moroccan Jews recite Birkat HaLevanah on the Saturday night that follows three whole days after the molad (the “rebirth” of the moon), while Sefardim and Hasidim say it on the first Saturday night after the seventh of the month.
There is a dispute regarding how to act when the seventh of the month begins on a Saturday night, but seven complete days from the time of the molad[168 hours] have not yet passed. Some authorities insist that we postpone the blessing until the next night, or the next Saturday night, which will fall out on the fourteenth of the month (Rashash, Rebbe Zalman of Liadi, Kaf HaChaim 426:61). Others contend that even if a few hours remain until the end of the seventh day from the molad, one may say Birkat HaLevanah(Knesset HaGedolah, Yechaveh Da’at 2:24). If people from different ethnic backgrounds pray together, and the seventh of the month falls out on a Saturday night, it is proper for everyone to recite Birkat HaLevanah, according to the opinion of the majority of poskim.
One who failed to say Birkat HaLevanah by the seventh of the month can say it until the end of the night of the fifteenth, because the moon is still full until then. Afterwards, it begins to wane, and therefore, the blessing cannot be said from the night of the sixteenth and onward (Shulchan Aruch 426:3).
Preferably, one should take into account the opinion of the Maharil, who holds that one may not say Birkat HaLevanah after half of the moon’s cycle has elapsed (14 days, 18 hours, and approximately 20 minutes from the time of the molad). This time rarely passes the beginning of the night of the fourteenth. By the night of the fifteenth, the moon’s cycle sometimes reaches the halfway mark, and sometimes not (Rama 426:3, Kaf HaChaim 53). Nevertheless, in practice, one who did not say the blessing by the fourteenth may say it until the end of the night of the fifteenth (Biur Halachah 426:3, Yabi’a Omer 8:42).
 See Beit Yosef and Shulchan Aruch 426:4, Bach and Mishna Berura ibid., Kaf HaChaim 61, Sefer Kiddush Levanah 3:1-2. Many Rishonim hold that the blessing should be said immediately upon the moon’s reappearance [at the beginning of the month]. R. Ya’akov Roke’ach writes in Shulchan Lechem HaPanim that this seems to be the opinion of R. Amram Gaon, Behag, Rif, Rambam, Rosh, and others. The Bach points out that the Talmud implies that one should not say Kiddush Levanah after the seventh day. The Rambam, as well, indicates that it is preferable to say it as early as possible. On the other hand, some poskim infer from Tractate Soferim (20:1) that one should not bless the new moon until it is possible to benefit from its light. Talmidei Rabbeinu Yonah, R. David Avudraham, the Kolbo, and others espouse this viewpoint. This is also the practical implication of the discussion cited above in note 23. According to Kabbalah, one should say the blessing after seven days. In practice, the custom of Ashkenazim is to bless the moon after three days have passed. This is also the custom of the Jews of Morocco and other North African communities (so writes Rabbi Mashash and many others). The majority of Sefardim, based on Kabbalah, as well as the Hasidim, are accustomed to reciting the blessing after seven days. Moreover, some Ashkenazim follow this custom l’chatchillah (preferentially), as the Chatam Sofer (Orach Chayim 102) and Aruch HaShulchan (426:13) write. Nonetheless, when the seventh falls out on a Saturday night, it seems preferable to recite Birkat HaLevanah then, even if seven complete days from the molad have not yet passed. Thi I because the moon’s light is already abundant and part of a day is regarded as an entire day. All the more so seeing that it is Motzei Shabbat, a joyous time which is suited for Birkat HaLevanah. Besides which, several poskim hold that one should recite the blessing as early as possible (Ramban and his adherents), while others assert that one should not say it later than the seventh of the month (Bach). Therefore, it is proper to say it on the night of the seventh, even if seven complete days have not passed since the molad. This is how the Knesset HaGedolah, Rama of Panow (78), Nahar Mitzrayim, Eliyah Rabbah, Eshel Avraham of Buchach, Maharsham, and others conclude (see Sefer Kiddush Levanah 3:8, with notes 27 and 29; Yechaveh Da’at 2:24).