(Mishnah): In a place where it is customary to sell small animals (such as sheep and goats) to idolaters, one may sell. In a place where it is customary not to sell them, one may not sell them.

In all places, one may not sell them large animals (such as oxen) calves and young donkeys, both uninjured and injured.

R. Yehuda permits selling them injured ones.

Ben Beseirah permits selling them a horse.

(Gemara) - question: Why would a Jew have a small animal to sell? Isn't it prohibited for a Jew to breed small animals in Eretz Yisrael?

Answer (R. Ba): When he bred them in an arid area 16 by 16 mil. The students wanted to suggest the one who rules that it is permitted to sell a small animal to an idolater as they are not suspected of bestiality, it is also permitted to allow one's animal to be alone with an idolater for the same reason. This disagrees with the Mishnah that teaches (further on) that one may not leave his animal at an inn of idolaters (because of this suspicion).

(R. Yona/ R. Elazar citing Rav): Even according to the one who said it is permitted to sell them, it is prohibited to leave one's animal secluded with them.

Question: What is the difference between selling and allowing seclusion?

Answer: When he sells him his animal, it becomes the animal of the idolater (who will not want to potentially cause his animal to become sterile by having relations with it); but when he allows the idolater to be secluded with his animal, it is still his animal and the idolater is not concerned.

The Mishnah taught that in a place where it is customary not to sell small animals, one may not sell them (to idolaters). Why is this? Because he removes this animal from the Mitzvah of giving the first shearings of its wool to the Kohen.

Question: So why is a goat prohibited?

Answer: Because he removes its offspring from the Mitzvah of giving the firstborn to the Kohen.

Question: So what if it is male?

Answer: Because he removes it from the Mitzvah of giving the various gifts (of the front leg, the cheek and the stomach) to the Kohen.

Question: If so, one should not be able to sell wheat to an idolater, as he removes it from the Mitzvah of separating Challah? And one should not able to sell wine and oil to an idolater as he removes them from reciting a blessing on them? (Rather, this line of reasoning cannot be true and the real reason that the custom in some places is not to sell a small animal to an idolater is as a decree lest one allow his animal to be secluded with an idolater.)

The Mishnah taught that in all places, one may not sell them large animals. Why does this prohibition apply to all and does not depend on custom? A large animal involves a potential sin offering (as a Jew many not have his animal do melacha on Shabbos) and a small animal does not involve a sin offering (as melacha is not usually done by small animals).

Question: But one milks and shears small animals (which are melachos)?

Answer: A large animal does melacha itself, but a small animal does not do the melacha of milking or shearing; it is done to it by a person (so if the idolater does so, the Jew does not transgress).

Answer #2 (R. Ami of Bavel citing Rabbanan): Sometimes the Jew sells the animal to the idolater for a trial period and the idolater returns it after three days, meaning that ultimately, the idolater worked with the Jew's animal.

Question: If so, only selling on trial should be prohibited, but not on trial should be permitted?

Answer: That (when not on trial) is prohibited because of this (on trial).

Question: If a person transgressed and sold a small animal to an idolater in a place where the custom is not to do so, do we penalize him that he must buy it back from the idolater, even if it will cost him double the price?

Answer: Just as we penalize for transgressing a clear prohibition (such as selling a large animal), so we penalize for transgressing the custom.

Question: From where do we know that we penalize for transgressing the clear prohibition (of selling a large animal to an idolater)?

Answer: A person once sold a camel to an Aramean. The case came before Reish Lakish and he penalized the man to pay up until double value to buy it back from the idolater.

(R. Yosi bar R. Bun): (Disagreed) They penalized the agent who made the deal and they called him the derogatory name "Berah Demasarsar l'Aramai" - "The son who makes deals with Arameans". (Note: The changes made in the following few entries are according to the actual text of the Tosefta in Bechoros 2:1.)

Reish Lakish follows R. Yehuda, as the Beraisa taught...

One who buys the offspring of a cow from an idolater, when the offspring was still unborn, or if a Jew transgressed and sold it to an idolater; or an idolater who brought in a Jew as a partner over the entire cow and entire foetus, or a Jew who brought in an idolater; or a Jew who received the animal of an idolater to rear and divided the offspring with the idolater; or vice-versa; in all these cases, it is exempt from the laws of the firstborn.

(R. Yehuda): Even one who transgressed and partnered with an idolater by receiving his animal to rear, if there is a firstborn calf, they evaluate it and give half of the value to a Kohen (as the Jew's half is owed to the Kohen).

One who transgressed and gave a pregnant cow to an idolater to rear and split the profits, he is penalized to be required to redeem it from the idolater, even if he will need to pay 10 times its value.

(Chachamim): Since the 'finger' of the idolater is in the middle, it is exempt from the laws of the firsborn.

Reish Lakish follows R. Yehuda but is more stringent than him - R. Yehuda only penalized for removing the offspring from the laws of the firstborn, which is a Torah commandment; but Reish Lakish penalized even for transgressing the law of selling a large animal to an idolater, which is a Rabbinic enactment.