It is a biblical commandment to recite Shema at night and in the morning, as the Torah states in the paragraphs of Shema and Ve-haya im Shamo’a: “When you lie down and when you rise.” It is also a mitzva to mention the Exodus during the day and at night, as the Torah states: “So that you remember the day you left Egypt every day of your life” (Devarim 16:3). The Torah seems to add a superfluous word (“kol yemei ĥayekha” instead of just “yemei ĥayekha”), from which the Sages derive that the mitzva to remember the Exodus is performed both during the day and at night (Berakhot 12b). For that reason, Va-yomer is also recited at night, since it mentions the Exodus at the end. Va-yomer, which discusses the mitzva of tzitzit, primarily applies to the day, and although one can fulfill the nighttime mitzva of mentioning the Exodus with other verses, common practice is to recall it by reciting Va-yomer, since it is familiar to all (Tosafot Yom Tov ad loc.). Combined with the first two paragraphs, it contains 248 words (above, 16:11), and by reciting all three paragraphs, one fully accepts the yoke of heaven (above, 16:4-5).
The Men of the Great Assembly added two berakhot before and two after the recitation of Shema. The first, Ha-ma’ariv Aravim, praises God for the changing times. The second, Ahavat Olam, praises God for loving Israel and giving us the Torah. The third, Emet Ve-emuna, praises God as our Redeemer. In the fourth berakha, Hashkiveinu, we ask God to protect us at night and watch over us when we sleep. Hence, Birkhot Keri’at Shema are comprised of seven blessings, three in Shaĥarit and four in Ma’ariv. Y. Berakhot 1:5 states that they were instituted based on the verse “Sheva ba-yom hilaltikha” (“I praise You seven times daily”) (Tehilim 119:164; see above, 16:12).
Since the mitzvot of Keri’at Shema, the recitation of its berakhot, and mentioning the Exodus are all time-bound commandments, women are exempt from them (see above, 16:3). The time for Shema begins at tzeit ha-kokhavim and lasts until ĥatzot (halakhic midnight). Be-di’avad, Shema may be recited with its berakhot until dawn. 1
Although women are exempt from positive time-bound commandments, one who wishes to voluntarily fulfill them is credited for it. Since women regularly recite the first paragraph of Shema before going to sleep as part of a prayer for protection, it is best that while saying it she has in mind to fulfill the mitzva of Keri’at Shema as well, thus performing the nighttime mitzva of Shema.
- Tzeit ha-kokhavim is the time when three medium-sized stars are visible. An uncertainty arises: Does this mean the time when people with good eyesight, who are experts on the positions of the stars, can see them or the time when people with normal vision can see them? In practice, according to the widespread custom, one may begin Ma’ariv twenty minutes after sunset. The time to recite the nighttime Shema, according to the Torah, is all night, but the Sages created a safeguard and required people to recite it by ĥatzot. Be-di’avad, one who did not pray in time has until dawn to recite. Peninei Halakha: Prayer 25:5 and 8 discusses this issue at length. ↩