1) SHMUEL'S STATEMENT
QUESTION: The Gemara discusses the statement of Shmuel at length. Shmuel states, "Any animal which must be left to die when it is a Korban Chatas is brought as a Shelamim when it is a Korban Pesach. Any animal which must be left to graze when it is a Korban Chatas is also left to graze when it is a Korban Pesach."
The Gemara questions Shmuel's statement from a case ("Avrah Shenasah") in which an animal which must graze if it was a Korban Chatas is nevertheless brought as a Shelamim when it is a Korban Pesach. The Gemara answers that Shmuel applies his rules only where an animal was lost (and another animal was designated as a Korban in its place, and then the lost animal was found). Any other manner in which an animal became invalid as a Korban is not subject to Shmuel's guidelines.
The Gemara later asks that there is no case of a lost Korban Chatas which must be left to graze. The Gemara answers that there is such a case when one designated two animals (one as the Korban Chatas and one as "Achrayus," an alternate in case something happens to the first). The first animal is brought as a Chatas, and the second is left to graze. The Gemara asks that according to Shmuel, a Korban Pesach that was designated as an alternate should also be left to graze. Why is the second Korban Pesach brought as a Shelamim?
The Gemara answers that Shmuel follows the view of Rebbi Shimon who says that the alternate Chatas must be left to die. (This is consistent with Shmuel's statement, for any animal that must die when it is a Chatas is brought as a Shelamim when it is a Korban Pesach.)
RASHI points out that the Gemara could have asked that it has already been established that Shmuel's rules apply only to cases of lost animals. The case of two Korbanos (where one was designated as "Achrayus") is not a case of a lost animal. Rashi explains that the Gemara had a different question to ask, and therefore it disregarded this issue.
However, Rashi later seems to contradict himself. The Gemara asks that if Shmuel agrees with Rebbi Shimon, why does he say that "any animal which must be left to graze when it is a Korban Chatas is also left to graze when it is a Korban Pesach"? According to Rebbi Shimon, there is no case of a Korban Chatas that is left to graze. The Gemara answers that Shmuel himself did not say the second part of the statement; he never discussed animals that must be left to graze.
Rashi asks why it is necessary for the Gemara to mention both points -- that Shmuel rules like Rebbi Shimon, and that he never discussed animals that must be left to graze. Once the Gemara says that Shmuel never said the second part of his statement, the Gemara does not have to say that he follows the view of Rebbi Shimon. Shmuel could also rule like Rebbi, who maintains that there are some types of Chatas which must graze, but the identical types of Korban Pesach are brought as Shelamim. Rebbi's opinion does not conflict with Shmuel's statement, because Shmuel never said that part of the statement.
Rashi answers that Shmuel's first statement implies that only Chata'os which must be left to die are brought as Shelamim when they are Pesachim. If Shmuel agrees with Rebbi, then this is not true. There is also a lost Chatas which is left to graze, which, when it is a Pesach, is brought as a Shelamim. Therefore, it must be that Shmuel follows the view of Rebbi Shimon.
What does Rashi mean? Rashi writes, just a few lines earlier, that the case of two animals designated as a Chatas ("Achrayus") is not a case of a lost animal, and therefore Shmuel does not include that case in his statement. Accordingly, there are no cases, even according to Rebbi, in which a lost Chatas would be left to graze, and a Pesach would be brought as a Shelamim. Thus, it is possible that Shmuel indeed follows the view of Rebbi.
(a) TOSFOS (DH k'd'Rebbi and DH Ela) disagrees with Rashi. Tosfos explains that the case of "Achrayus" is comparable to a case of an animal that was lost. Since the second animal was not designated as a Korban in the first place, it is as if it was "Nidcheh," just like an animal that was lost. Furthermore, if the second animal is lost before the first one is sacrificed, when found it will not be put to death. It will be sent to graze because it was only a back-up for the first animal, and was never designated to be offered. Since that case also applies when the animal was lost, it is included in Shmuel's statement. Therefore, Shmuel cannot rule like Rebbi.
(b) RASHI himself may understand the Gemara like the RASHBAM (quoted by TOSFOS DH Ela). The Rashbam explains that now that the Gemara says that Shmuel agrees with Rebbi Shimon, it disregards the previous answer (that Shmuel discusses only cases of lost animals). Rather, now that Shmuel rules like Rebbi Shimon, he refers to all types of Chata'os which die. Accordingly, his statement also includes the case of "Achrayus," as well as the case of "Chatas she'Avrah Shenasah." In those cases, Rebbi and the Rabanan rule that the Chatas must graze, even though if that animal was a Korban Pesach it would be brought as a Shelamim. This is contrary to Shmuel's ruling. Therefore, it must be that Shmuel sides with Rebbi Shimon and maintains that in all cases the Chatas must die and the Pesach is brought as a Shelamim. This is consistent with Shmuel's statement.
However, according to this explanation, Shmuel's statement is not accurate. If a Pesach was lost and then found before midday (Chatzos) on the fourteenth of Nisan, the Mishnah says it must be left to graze, even though Rebbi Shimon rules that a Chatas (a lost Chatas that was found before the new Chatas was brought) must die. According to Shmuel's rule, the Pesach should be brought as a Shelamim since the Chatas must die.
The RASHBAM explains that Shmuel does not mean that in every case of a Chatas that must die, the animal is brought as a Shelamim when it is a Pesach. Rather, he means that for every category of Chatas that must die, the corresponding Pesach is sometimes brought as a Shelamim. A lost Chatas which is found must be put to death, and similarly there exists a case in which a lost (and found) Pesach is brought as a Shelamim -- if it was found after Chatzos.
(It is important to note that Rashi later (DH Ka Mashma Lan) seems to reject the explanation of the Rashbam. He says that even according to the Gemara's conclusion, Shmuel discusses only lost animals and not other types of Chata'os which must die. However, the DIKDUKEI SOFRIM writes that these words do not appear in the manuscripts of Rashi (from the word "v'Hashta" until the last word, "Nimtza"). These words might have been added later by a student, while Rashi indeed learns the Gemara like the Rashbam.
This omission in the text of Rashi will also answer the question of the RASHASH, who asks that this comment of Rashi contradicts his words later on 98a, DH Hachi Garsinan Ravina. If this part of Rashi was authored by a student, then there is no contradiction. Whoever wrote these words in the commentary of Rashi might have learned the Gemara later (98a) like the Me'iri, and not like the way Rashi explains there.)