As we learned on yesterday’s daf the offspring of a korban shelamim – a peace offering – is in the same category as the original animal and can be brought as a sacrifice. The Mishna on today’s daf brings the opinion of Rabbi Eliezer who disagrees and rules that the offspring cannot be sacrificed. In conclusion, the Mishna tells of Rabbi Pappeyas who testified that his family had an animal that was eaten on the holiday of Pesaḥ as a korban shelamim while its offspring was eaten as a korban shelamim on a later holiday – apparently the following Sukkot. Clearly Rabbi Eliezer’s opinion was not accepted in practice.
In examining the testimony of Rabbi Pappeyas the Gemara relates that there is a Torah law that requires a person who accepts upon himself to bring a sacrifice to bring it without delay (Devarim 23:22), and that Rava rules that once a single one of the shalosh regalim – the three pilgrimage holidays – passes, the person who does delay transgresses this mitzva on a daily basis.
Two explanations are offered by the Gemara. Rav Ashi suggests that Rabbi Pappeyas was referring to the holiday of Shavuot when the second animal was sacrificed, which is the first opportunity to sacrifice it after Pesaḥ. Rav Zevid quotes Rava as saying that in this case the animal (or, perhaps, the owner) was ill and could not bring the sacrifice on Shavuot, so it was left for the following Sukkot.
When this topic is discussed in Massekhet Rosh HaShana (daf 6a), the Gemara appears to take for granted that the commandment to bring a sacrifice “on time” requires that it be brought within the cycle of holidays – Pesaḥ, Shavuot and Sukkot – and not in the first holiday that occurs. Some distinguish between the positive commandment to bring the sacrifice as soon as possible, which is understood as a requirement to bring it at the first holiday, and the negative commandment which only applies after a full cycle of holidays has passed.