Hullin, Chapter Ten, Mishnah Three
1) A first-born got mixed up with a hundred other animals:
a) If a hundred [and one] persons slaughtered them all, they are all exempt from the gifts.
b) If one person slaughtered them all, only one animal is exempt from the gifts.
2) If a man slaughtered an animal for a priest or a non-Jew, he is exempt from the gifts.
3) If he had a share [in the animal] with them, he must indicate this by some sign.
4) If he said, Except the gifts he is exempt from giving the gifts.
5) If he said, Sell me the entrails of a cow and among them were the gifts, he must give them to a priest and [the seller] does not need to reduce the price.
6) But if he bought them from him by weight, he must give them to a priest, and [the seller] must reduce the price.
Section one: As we learned in mishnah one, one is exempt from giving the priestly gifts from consecrated animals. This includes even a first-born that has a defect that allows one to slaughter the animal and eat it. The problem presented in our mishnah is that this first born was mixed up with many other non-sacred animals. If each animal was slaughtered by a different person, meaning each animal was owned by a different person, they are all exempt from giving the priestly gifts, because each person can claim that his animal was not the first-born.
However, if they all belong to one person, then he must give the priestly gifts from all but one animal, for one animal is surely exempt.
Section two: An animal owned by a priest or by a non-Jew is exempt from the priestly gifts. If one slaughters an animal owned by a priest or a non-Jew for the priest or non-Jew the animal is exempt.
Section three: If a person jointly owned an animal with a non-Jew or priest, the animal is still exempt from the priestly gifts. However, in order that people should know why gifts are not being given from this animal, he must make a sign on the animal that it is jointly owned by someone who is exempt.
Section four: The next few sections deal with sales of animals. If a priest sells an animal to a non-priest and he says that he is selling the animal but not the gifts, (the shoulder, cheeks and stomach), then the Israelite does not need to pay the value of these parts of the animal because they were never his.
Section five: If a person tells a butcher to sell him the entrails of an animal, and among the entrails are gifts that must be given to the priest, the purchaser must give them to the priest and the seller need not reduce the price. This is because the purchaser knew that he was not going to get to keep all of that which he bought. In other words, it was already reckoned into the price.
Section six: However, if he buys by weight, then he is anticipating that all that he buys will be his. In this case, if the seller gives the buyer priestly gifts, he must reduce the price.