Zevachim Daf 69 זבחים דַף 69

A Baraisa darshens about an invalid מליקה (e.g., at night) that the bird is still not metamei בבית הבליעה: the passuk about טומאת נבילה mentions "טריפה", which is extra, comparing the tumah of נבילה with a טריפה: מה טריפה שאין מתרת את האיסור – just as becoming a tereifah does not permit any prohibition, אף כל שאין מתרת את האיסור – so too a bird is metamei as a נבילה only when its killing does not permit any prohibition. Since an invalid מליקה permits the bird to be left on the מזבח if it is placed there, it is not metamei בבית הבליעה. According to the same standard, מליקה of קדשים birds בחוץ – outside the Mikdash, and מליקה of chullin birds (inside or outside the Mikdash), are metamei בבית הבליעה, since מליקה does not permit any prohibitions in these cases.

Another Baraisa darshens this superfluous word "טריפה" in the passuk about טומאת נבילה to teach: מה טריפה שווה בפנים כבחוץ – just as tereifah is the same inside the Mikdash and outside it (i.e., both are forbidden to eat), אף כל שוות בפנים כבחוץ – so too birds become נבילה wherever their נבילה status for this method of killing is the same inside as outside. This excludes the shechitah of chullin birds inside the Mikdash; since their shechitah outside the Mikdash certainly removes their tumah (even if the bird is discovered a טריפה, because this Baraisa follows Rebbe Meir’s opinion below), it also cannot be a נבילה when shechted inside. Regarding the shechitah of kodashim birds, Rava explains why shechitah outside the Mikdash prevents tumah: אם הועילה לו שחיטת חוץ לחייבו כרת – if its shechitah is effective for him to make him liable for kares (for shechting a korban בחוץ), לא תועיל לו לטהרה מידי נבילה – should it not be effective for him to purify it from [tumah of] neveilah? Since it is not metamei when shechted outside, it is also not metamei when shechted inside, הואיל ולא שוו בפנים כבחוץ – since their נבילה status (for shechitah) is not the same inside as outside.

The next Mishnah states: מלק ונמצאת טריפה – if one performed מליקה and [the bird] was found to be a tereifah, Rebbe Meir says it is not metamei בבית הבליעה, but Rebbe Yehudah says it is. Rebbe Meir argued with a kal vachomer: if for an animal, whose נבילה is metamei with מגע – contact and משא – carrying, yet שחיטתה מטהרת טריפתה מטומאתה – its shechitah purifies a tereifah from its tumah (i.e., a טריפה which is shechted is not metamei as a נבילה), then certainly for a bird, whose נבילה is only metamei בבית הבליעה, its שחיטה would purify its טריפה from being metamei as נבילה! He then extends this to מליקה, since each prepares a bird for consumption (for chullin and korbanos, respectively). Rebbe Yose agrees that שחיטה would prevent a טריפה bird’s tumah, but holds מליקה would not, because of the principle of "דיו" (i.e., not deriving from a kal vachomer more than the law in its original source). The Gemara proves that Rebbe Meir certainly agrees with the principle of "דיו", since it is sourced in a passuk. Therefore, it proceeds to explain how Rebbe Meir and Rebbe Yehudah darshen their opinions from pesukim.