Rather, it refers to leavened bread, which is prohibited all seven days of Passover in the generations following the Exodus. The Gemara asks: Does this prove by inference that during the Passover of Egypt, leaven was prohibited for only one night and not more? But wasn’t it taught in a baraita that Rabbi Yosei HaGelili says: From where is it derived with regard to the Passover of Egypt that its prohibition of leavened bread applied for only one day? The verse states: ''No leavened bread shall be eaten'' (Exodus 13:3), and juxtaposed to it the verse states: ''This day you go forth'' (Exodus 13:4), to teach that the prohibition of leaven applied in Egypt for only one day. In any event, the prohibition applied for an entire night and day, and not just one night.

Rather, this question must be answered by saying that this is what it said in the mishna: The Paschal lamb was eaten in Egypt on one night, and the same is true of the Paschal lamb of later generations; and its prohibition against leavened bread applied the entire day, and on Passover in later generations it applies to all seven days of the Festival.

MISHNA: Rabbi Yehoshua said: I heard two rulings from my teachers: One ruling was that the substitute of a Paschal lamb is sacrificed as a peace-offering after Passover, and another ruling was that the substitute of a Paschal lamb is not sacrificed as a peace-offering after Passover; and I cannot explain these two rulings, as I do not remember the circumstances to which each ruling applies.

Rabbi Akiva said: I will explain: With regard to a lamb that is separated as a Paschal lamb and is then lost, leading the owner to separate another animal as its replacement, and is later found before the slaughter of the replacement Paschal lamb, it is left to graze until it becomes unfit [yista’ev] and disqualified for use as a sacrifice. It is then sold and becomes unconsecrated, and the owner must bring a peace-offering with its proceeds. And so too, the same is true with regard to its substitute: If one separates another lamb as a substitute for this replacement, the sanctity of the original lamb extends to the substitute as well. In the case outlined above, the substitute would graze, just like the replacement, until it developed a blemish and would then be sold. This is the circumstance in which the substitute of a Paschal lamb is not sacrificed.

On the other hand, if the lost lamb is found after the slaughter of the replacement Paschal lamb, it itself is sacrificed as a peace-offering, and so too, its substitute is sacrificed, which explains the ruling that the substitute of a Paschal lamb is sacrificed as a peace-offering.

GEMARA: The Gemara questions the explanation of Rabbi Akiva: If so, let the mishna say these halakhot more simply, as follows: The Paschal lamb itself is sacrificed and the Paschal lamb is not sacrificed. According to Rabbi Akiva’s explanation, the same rule applies to both the lamb and its substitute. What additional point is Rabbi Yehoshua making by speaking about the substitute? The Gemara answers: This comes to teach us through this formulation that there is a case of a substitute Paschal lamb that is not sacrificed. One might have thought that a substitute Paschal lamb is always treated as a peace-offering, even when it was substituted before the time of the slaughter; therefore, the mishna states that there is an instance in which it cannot be sacrificed because it is a substitute for a Paschal lamb that itself cannot be sacrificed.

It was stated that there was a dispute between amora’im about the proper text of the mishna. Rabba said: We learned the opinion of Rabbi Akiva in the mishna as referring to the distinction of whether the lamb is found before the slaughter of the replacement lamb or after the slaughter of the replacement lamb. Rabbi Zeira said: We learned that it depends upon whether it is found before midday or after midday. Midday is the time that determines the status of an animal as a Paschal lamb; therefore, if the lamb is found after midday, even if it is found before the slaughter of the replacement Paschal lamb, its identity as a Paschal lamb is not firmly established and it may be sacrificed as a peace-offering.

The Gemara asks: And according to Rabbi Zeira, isn’t the mishna teaching explicitly that it depends upon whether the lamb is found before the slaughter of the replacement Paschal lamb? How can he disagree with the mishna? The Gemara answers: Say that according to Rabbi Zeira, the mishna must be interpreted as referring not to the act of the slaughter itself but to a lamb that is found before the earliest time for the slaughter of the Paschal lamb, which is midday.

The Gemara notes that this dispute among the amora’im is like the following dispute between tanna’im in a mishna: The Paschal lamb that is found before the slaughter of its substitute shall be left to graze until it becomes unfit; it is then sold, and the proceeds are used to purchase an animal that will be sacrificed as a peace-offering. If it is found after the slaughter, it itself is to be sacrificed as a peace-offering. This is parallel to the explanation of Rabba. Rabbi Eliezer says that if it is found before midday it shall be left to graze, but if it is found after midday it is to be sacrificed as a peace-offering, which is parallel to the explanation of Rabbi Zeira.

It was stated in the mishna that if the original lamb is found after the slaughter of the replacement Paschal lamb, one should bring the original lamb as a peace-offering, and the same applies to its substitute. Rava said: They taught that the substitute may be sacrificed as a peace-offering only when the original lamb was found after the slaughter of the replacement lamb and one performed the substitution after the slaughter, when the original lamb itself was fit to be offered as a peace-offering. But if the original lamb was found before the slaughter, even if one performed the substitution after the slaughter of the replacement lamb, the substitute lamb may not be sacrificed as an offering. The reason for this is that the original lamb may no longer be sacrificed as an offering and must be left to graze until it develops a blemish. Therefore, the sanctity of its substitute comes on the strength of deferred sanctity, and the substitute may not be sacrificed.

Abaye raised an objection to Rava based on a baraita: With regard to the verse: ''If he brings a lamb for his offering'' (Leviticus 3:7), what is the meaning when the verse states: ''If he brings a lamb''? What is added by the word ''if''? It comes to include the substitute of a Paschal lamb after the slaughter of the replacement Paschal lamb and teaches that it is offered as a peace-offering.

Abaye clarifies the meaning of this baraita: What are the circumstances of the case under discussion? If we say it is a case in which the lamb was found after the slaughter and one performed the substitution after the slaughter, it is obvious, as any Paschal lamb found after the slaughter of its replacement becomes a peace-offering; in that case, why do I need a verse to teach this halakha? Rather, is it not addressing a case in which the original lamb was found before the slaughter of its replacement and one performed the substitution after the slaughter of the replacement, and nonetheless the substitute lamb may be offered as a peace-offering, in opposition to Rava’s ruling?

The Gemara responds: No; actually it can be explained as referring to a case in which the original lamb was found after the slaughter of the replacement, and one performed the substitution after the slaughter. It is indeed obvious and no verse is necessary to teach this halakha; the verse cited is not the source for this ruling but is a mere support.

The Gemara asks: But then for what purpose does this verse come? The Gemara answers: As it was taught in a baraita: The word ''lamb'' comes to include the Paschal lamb in the requirement that the fat tail be offered on the altar, as this halakha is not explicitly mentioned in the verses that relate to the Paschal lamb.

The baraita continues: When it says: ''If he brings a lamb,'' which alludes to additional types of offerings it comes to include a lamb consecrated as a Paschal lamb whose first year has passed and is therefore too old to be offered as a Paschal lamb, or peace-offerings that come due to a Paschal lamb, both those separated as a substitute for a Paschal lamb and those that were actually consecrated as a Paschal lamb but the owner fulfilled his obligation with a different Paschal lamb, in all the mitzvot of peace-offerings. These offerings are no longer considered Paschal lambs and are treated as peace-offerings in every way. Therefore, they require leaning and libations and the waving of the breast and thigh.

The baraita continues: And when it says: ''And if his offering is a she-goat'' (Leviticus 3:12), it interrupted the previous matter and taught that the offering of a she-goat does not require the fat tail to be burned on the altar.

The Gemara has concluded one version of the dispute between Rava and Abaye. However, some teach this dispute with regard to the first clause of the mishna, which states that a Paschal lamb which is first lost and then found before the slaughter of the replacement Paschal lamb must be left to graze until it becomes unfit, and it is then sold, and one must bring a peace-offering with its proceeds; and likewise, the same is the case with regard to its substitute.

With regard to this halakha, Rava said: They taught this halakha only in a case where the original lamb was found before the slaughter and one performed the substitution before the slaughter; but if the original lamb was found before the slaughter and one performed the substitution after the slaughter of the replacement lamb, its substitute is offered as a peace-offering. What is the reason for his opinion? The slaughter of the replacement establishes a halakhic reality only with regard to something which is fit for it; in other words, it is only with regard to a Paschal lamb itself that it matters whether it was found before or after the slaughter. However, with regard to something that was not fit for it, such as the substitute, which cannot be offered as a Paschal lamb in any event, the slaughter does not establish its status. Therefore, it can later be sacrificed as a peace-offering.

Abaye raised an objection to Rava based on the same baraita quoted previously: What is the meaning when the verse states: ''If he brings a lamb''? It comes to include the substitute of a Paschal lamb after Passover, which is offered as a peace-offering.