Siman 458

The Tur wrote: One does not begin to occupy oneself with the bread on the fourteenth until after six hours. And it is found in a responsum: A case occurred where one baked beforehand... and our teachers forbade the matzah. For it is juxtaposed with the Pesach offering ("with matzot and bitter herbs"), and since the Pesach offering is not slaughtered until after six hours—so too the matzah. However, our teacher Eliezer the Great and our teacher Shmuel HaKohen permitted it. But ab initio one should be careful because "a commandment is beloved in its proper time." And the Avi HaEzri brought in the name of the Tosefta that one fulfills the obligation with old matzah... and he wrote that the Yerushalmi disagrees... and since the Yerushalmi forbids it—it is proper to be stringent... and a Shabbat that falls on the eve of Pesach—they should bake on the conclusion of Shabbat... and my master, my father the Rosh, of blessed memory, used to bake from the eve of Shabbat... Thus far his words. And similarly wrote the Mordechai at the end of the first chapter of Pesachim and the Or Zarua the Great (siman 250). And they conclude with permission, see there.

And the opinion of those who forbid is very, very puzzling, for the comparison to the Pesach offering is only regarding eating, and not regarding preparation. For if it were not so—let it override Shabbat like the Pesach offering. Furthermore: it is an explicit Mishnah that one fulfills the obligation with the loaves of a todah offering, and the loaves of a todah offering are forbidden to be baked on the eve of Pesach because of the chametz within them. And also in the Yerushalmi it is explicitly stated to the contrary, and it is in the second chapter (halacha 4) which says: because he was not meticulous with the matzah-process. But if he was meticulous—it is valid. And these arguments have already been answered against those who forbid. And it is possible to somewhat settle this, for behold, the comparison is only according to Rava Elazar ben Azariah, who holds that the Pesach offering is only eaten until midnight. And we say at the end of Pesachim: Rava said: According to the words of Rabbi Elazar ben Azariah, if one ate matzah after midnight—he has not fulfilled his obligation, for it is compared to the Pesach offering, see there. And according to this, it is possible to say that the Mishnah of the loaves of a todah offering, and the Tosefta, and the Yerushalmi—follow Rabbi Akiva, that the Pesach offering is eaten all night. And according to this, he does not need a comparison for the time of eating, for behold it is written "in the evening you shall eat matzot," which implies the entire evening. Therefore, according to Rabbi Elazar ben Azariah who requires a comparison—consequently we compare it also to the baking. But according to Rabbi Akiva, it is not so. And the Rambam in the sixth chapter ruled like Rabbi Akiva, and the Tosafot at the end of the second chapter of Megillah and the end of the fifth chapter of Zevachim ruled like Rabbi Elazar ben Azariah. And according to this, it can be said that these Geonim hold like the Tosafot, and therefore the Rambam did not mention this at all. And if it is difficult: that if so, its baking should also override Shabbat? It is not difficult at all, because even the loaves of a todah offering and all the meal-offerings—do not override Shabbat.

It appears more likely in my humble opinion that this is because it is known that in ancient times they did not bake all the matzot before Pesach, but rather they would bake bread each day of the days of Pesach for that day. To the extent that the Tur wrote as a novel matter, and this is his wording: And I saw in Barcelona among those who are meticulous, that they would bake everything they needed for the festival before the festival, so that if a minute amount of chametz were to be mixed with it – it would be nullified before its prohibition. Thus far his words, and this is like our custom. And he wrote this as a novel matter. Therefore, when they would bake every day, and eat warm bread, if so, why should the matzah of the mitzvah be diminished such that they would not bake it close to the eating, which is after midday? And all the more so since they wrote that there is venom in the maror and the warmth nullifies the venom (Or Zarua ibid.). Therefore, they baked close to nightfall, and also because "a mitzvah is beloved in its time." And also so that they would enjoy the matzah in the evening, for warm bread is much better than cold bread. For they baked thick matzot, not like ours, and the cold is difficult to eat. And it was an enhancement of the mitzvah. And the comparison they stated – it is a mere support, and as a remembrance of the Pesach sacrifice. And that which they prohibited for one who baked before the sixth hour – it is to create a fence around the matter, in the manner of the ancients who were diligent in mitzvot, and careful with the customs of Israel. But for us, who bake before Pesach – there is no reason for the custom. Therefore, in truth, nowadays only a few of those who are meticulous practice this, and all of Israel do not know of this at all (so it appears in my humble opinion).

This is the wording of our teacher, the Beit Yosef: It is the custom not to knead the matzah of mitzvah on Erev Pesach until after six hours, which is the time of the offering of the Pesach sacrifice. And on the fourteenth that falls on Shabbat – they knead on Erev Shabbat after six hours. Thus far his words. And they had further customs: that they would bake the three matzot of the Seder from one isharon, and they would mark them to know which is first and which is last, as I have written in siman 475. And they would bake further matzot, and they were called "safekot," meaning: if the first ones become disqualified – these will be in their place. And at the time when they would bake on Yom Tov, it was forbidden to bake from the first day of Yom Tov for the second. And since among us all these do not exist, therefore there is no need to write them. (See the Shulchan Aruch of the Gr"z who explained them. And perhaps in his days there was still a memory of this, but it is not so now.)