One fulfills the Torah obligation of Zakhor by invoking the sanctity of Shabbat and specifying that it commemorates the creation of the world and the Exodus from Egypt. However, the Sages wished for everyone to fulfill this mitzva using a precise and perfect text, so the Men of the Great Assembly formulated a berakha that declares the sanctity of Shabbat. To ensure that kiddush would be both dignified and pleasurable, they mandated that it be recited over a cup of wine prior to a meal. Some maintain that the Torah requires that kiddush be recited over enjoyable food or drink. It is customary to recite the additional verses of Va-yekhulu (Bereishit 2:1-3) before kiddush (see above 5:12).
Many poskim maintain that Zakhor obligates us to mark the end of Shabbat as well as its beginning. With the onset of Shabbat, there is a mitzva to invoke its sanctity and essence, while when it ends there is a mitzva to identify the difference between the sacred Shabbat and the mundane weekdays. Therefore, according to many poskim, havdala, recited at the end of Shabbat, is a Torah obligation. Like kiddush, this Torah obligation can be fulfilled with words alone, while the Sages ordained that it be said over a cup of wine (Rambam; MB 296:1; see below 8:1).
The Sages mandated that kiddush be recited on Shabbat day as well, to honor the day and differentiate it from weekdays. By beginning the meal with kiddush, we make it clear that this is a special and important meal; thus we are reminded of the sanctity of Shabbat. However, since this is not the primary fulfillment of Zakhor, the Sages did not formulate a special berakha in honor of Shabbat. Rather the berakha on wine (Ha-gafen) is recited over a cup of wine. The custom is to say a few Shabbat-related verses beforehand. This kiddush is referred to as “Kidusha Raba” (“The Great Kiddush”), which is a type of euphemism, as in fact it is the Friday night kiddush that is the important one (MB 289:3).
Even though the meal eaten on Shabbat day is considered more important than the nighttime meal (as explained below, 7:4), the mitzva of Zakhor is nevertheless fulfilled though the kiddush at night, because the mitzva is to mark Shabbat as it begins. Thus, after one finishes praying, he should hasten to make kiddush (SA 271:1, 3). One who was unable to make kiddush Friday night has not lost out on the mitzva. Rather, he should make kiddush in the morning before eating his first meal. He should recite the Friday night kiddush but leave out the verses of Va-yekhulu, since they are specifically connected to the evening (SA and Rema 271:8). If he did not make kiddush before his meal in the morning, there is still a mitzva to make kiddush as long as the sun has not set. He should make sure to eat afterward (as will be explained below, section 10).
Since according to Torah law one can verbally fulfill the obligation of Zakhor, some maintain that with the recitation of the middle berakha of the Amida at Ma’ariv (which invokes Shabbat), one has already fulfilled this obligation (MA). However, others question this, for two reasons. First, people do not generally intend to fulfill the mitzva of Zakhor with this prayer, and we maintain that mitzvot require intent (SA 60:4). Second, it is possible that one must mention in kiddush that Shabbat is a commemoration of the Egyptian Exodus. In the Amida, the Exodus is not juxtaposed with the sanctity of Shabbat. Therefore, in practice, we fulfill the Torah commandment in accordance with the Sages’ directives by making kiddush over wine (MB 271:2; BHL ad loc.). Furthermore, we have already seen that some authorities maintain that fulfilling the Torah obligation requires wine (see n. 1).