1. If someone sold food which turned out to be forbidden

The next Mishnah states that if one shechted a bechor and sold its meat, and it emerged that he did not show it to an expert, מה שאכלו אכלו – what [the buyers] already ate, they ate, ויחזיר להם הדמים – but he must refund the full purchase price to them, as a penalty for selling forbidden food. Whatever they did not eat must be buried, and they are refunded. In a Baraisa, Rebbe Shimon ben Elazar argues: דברים שהנפש קצה בהן – if the sold food turned out to be things which are repulsive to people, such as neveilah or insects, the seller must refund the buyers, because they did not benefit from what they ate. But if it turned out to be forbidden food which is not repulsive to people, such as bechor meat or יין נסך, ינכה להם את הדמים – he deducts from their refund the value of what they already ate and benefited from. This Tanna holds no penalty was imposed on one who sold forbidden foods to a Jew. [The Gemara proceeds to explain why the buyer should pay for eating food which was forbidden for the seller himself to use.]

1. על אלו מומין שוחטין את הבכור: blemishes of the ear

The sixth Perek begins: על אלו מומין שוחטין את הבכור – we may shecht a bechor based on the following blemishes: if its ear was notched in the cartilage, but not in the skin; if the ear was split, even if none of it was missing; if it was punctured the size of כרשינה [a kind of bean], or if it dried up. The Tanna Kamma defines “dried up” as where it would not emit a drop of blood if pierced, and Rebbe Yose ben HaMeshullam says it means it would crumble if handled. Although the passuk only mentions פסח – lame and עור – blind as מומין, it begins with the broader phrase "כי יהיה בו מום" – if it shall have a blemish, and concludes with the broader phrase "כל מום רע" – any bad blemish, which is "ריבויא" – an inclusionary term, and includes even מומין which do not בוטל ממלאכתו – impair its function (such as notched ear cartilage). However, מומין שבסתר – hidden blemishes are not considered מום רע – a bad blemish. A מום עובר – temporary blemish does not permit a bechor for shechitah, because since a Baraisa darshens that one cannot redeem a korban based on a מום עובר, certainly it does not permit shechting a bechor. An alternate explanation is given.

1. The puncture size for permitting shechitah vs. disqualifying a Kohen

In a Baraisa, the Tanna Kamma says that an ear puncture the size of a כרשינה permits a bechor for ordinary shechitah, but Rebbe Yose bar Rebbe Yehudah says בכעדשה – even the size of a lentil. [These sizes are nearly identical.] The Gemara objects: in another Baraisa, Rebbe Yose bar Rebbe Yehudah says that רציעה – piercing the ear of an עבד עברי who wishes to remain a slave may be performed with a needle. Yet, the Chochomim say in the סיפא that an עבד עברי who is a Kohen cannot undergo רציעה, because it would render him a בעל מום (because they hold the upper ear is pierced). This proves that even a needle-sized puncture, which is smaller than a כעדשה, is also considered a מום!? The Gemara answers: כאן לשחוט – here (the Baraisa about a bechor’s מום) is the size to shecht it as an ordinary animal, and requires the size of a כעדשה. כאן לפסול- Whereas here (the Baraisa about a Kohen’s מום) is the size to disqualify an animal from being a korban, or a Kohen from performing avodah. For this, even the size of a needle suffices.