It is well known that the Gaon of Vilna maintained that eating matza all Pesach is an optional mitzva. It is related (Ma’aseh Rav 175) that he accorded immense value to this mitzva. In fact, he would make a point of eating se’uda shelishit on the last day of Pesach (although he did not usually eat se’uda shelishit on Yom Tov), in order to fulfill the mitzva of eating matza in its waning moments before it expired.
If we indeed assume that there is a mitzva to eat matza all Pesach, we must ask why there is no berakha attached to it. On Sukkot, for example, there is no obligation to eat in the sukka throughout the festival; the obligation to eat in the sukka applies only on the first night. Thereafter, there is only a prohibition against eating anything substantial outside the sukka, and technically, one could avoid eating in the sukka throughout the remainder of Sukkot by living the entire week on snacks. If, however, one does eat in the sukka, he fulfills a mitzva and also recites a berakha. Why should we not similarly require a berakha over the consumption of matza after the first day of Pesach?
This question, originally posed by the Ba’al Ha-Maor (end of Pesachim), has become the subject of much discussion, and various answers have been suggested. The Michtam (Sukka 27a) and the Meiri (Pesachim 91b) reject the entire thesis and maintain that there is no mitzva at all to eat matza after the first night of Pesach.
By contrast, the Sedei Chemed (Chametz U’matza 14:10) cites a prevailing custom to recite a berakha, and the Netziv (Meishiv Davar 77) expresses uncertainty as to whether such a berakha would be considered a berakha le-vatala (an unnecessary berakha). In any event, this custom of making a berakha has been resoundingly rejected (see Responsa Yechaveh Da’at 1:22). The Ba’al Ha-Maor himself answered by saying that one need not eat matza the rest of Pesach, as it is possible to subsist on rice (for those whose custom permits it) or other foods. However, since a person cannot refrain from sleeping for an entire week, one must be in the sukka at some point during the week, and this mitzva therefore requires a berakha.
It is told that certain people who were known as extremely meticulous in mitzva observance did not eat matza at all after the first night of Pesach. Apparently, they were concerned about the intricacies of baking matza and feared that it could become chametz quite easily. Rav Eliezer Waldenberg (Responsa Tzitz Eliezer 13:65) disputed this position very strongly, for a number of reasons. He thought that there was an inherent contradiction in this practice.
If the adherents of this custom were truly afraid that the matza was not baked according to Halakha, how could they eat it on the first night of Pesach? Furthermore, Rav Waldenberg argued that there is a mitzva to eat “pat” (bread or matza) every day of Pesach, especially Shabbat and Yom Tov. How could they ignore this obligation? If we accept the opinion of the Chizkuni and Vilna Gaon, then the followers of this practice also negate the fulfillment of eating matza all Pesach.
Rav Waldenberg also cites an opinion that, given the Karaitic doctrine requiring eating matza all Pesach (following the Torah’s command, “You should eat matza seven days,” Shemot 12:15), there were those who refrained from eating matza after the first night to demonstrate their opposition to the Karaitic position. Nevertheless, Rav Waldenberg strongly advised eating matza all week.
We have shown that there is some dispute as to whether or not there is a mitzva to eat matza throughout Pesach. On the first night of Pesach, however, everyone agrees that there is an obligation to eat matza. In general, any mitzva of the Torah requiring eating involves the eating of a “ke-zayit” (an olive-sized portion). The mishna (Pesachim 10:1) says that a waiter who took a moment at the seder to recline and eat a “ke-zayit” of matza has fulfilled his obligation. The Maharal of Prague (Gevurot Hashem, 48) inferred from the formulation of this halakha that the waiter fulfills his requirement only be-di’avad (ex post facto); he satisfied the minimum requirement of eating while reclining. However, the mitzva to eat matza on the night of the fifteenth includes not just one ke-zayit, but all the matza that one eats that night, and therefore all the matza should be eaten while reclining. He says that this is the position of the Rambam, as well.