신명기 16:2 할라카: Mishneh Torah, Negative Mitzvot & Sefer HaChinukh

Not to eat leavened bread after mid-day on the fourteenth (of Nissan), as it is said, “Thou shalt eat no leavened bread with it^**The previous verse (Deut. 16:2) reads “Thou shalt sacrifice the Paschal offering unto the Lord, thy God”. No leaven must be eaten by the Israelite when the Paschal sacrifice is offered up (Maimonides’ Sefer-Ha-Mitzvoth on this precept).” (Deut. 16:3).

To not leave over from the festive (chagigah) sacrifice to the third day: To not leave over anything from the festive sacrifice of the fourteenth day until the third day — and that is the sacrifice that comes with the Pesach [sacrifice] to increase the joy — but rather to eat it all within two days, which are the fourteenth and fifteenth. And about this is it stated (Deuteronomy 16:4), “and none of the meat of what you slaughter on the evening of the first day shall be left to the morning.” And the received (traditional) understanding came upon this (Pesachim 71a) that the verse is speaking about the festive [sacrifice] that comes with the Pesach, [to say] that the time of its eating is up to two days. And about this festive [sacrifice], Scripture stated (Deuteronomy 16:2), “And you shall slaughter the Pesach to the Lord, your God, flock and cattle” — meaning to say, that with the Pesach, he brings another sacrifice; meaning to increase the joy.