פירוש על בכורות 1:1

הלוקח עובר חמורו של נכרי – when it is in the womb of its mother and it is a firstling (i.e., male or female). And for this reason, it (i.e., the Mishnah) took [the words], “the fetus of his donkey,” for there is no holy unclean animal with regard to its first-born other than the firstborn of a donkey alone, but since the words are few of the firstborn of the donkey, he decided and permitted it. But all of these other chapters speak of a first born of a pure animal.

Introduction Our mishnah teaches that donkeys owned, or even partially owned, by non-Jews are exempt from the obligation to have their first-born redeemed.

אף על פי שאינו רשאי – to sell to a heathen a large animal, because of work on Shabbat that would be performed by it (see Tractate Avodah Zarah, Chapter 1, Mishnah 6 – where the Halakha is established that it is forbidden to sell a heathen a large animal – originally owned by an Israelite).

[An Israelite] who buys a fetus of a donkey belonging to a non-Jew or who sells one to him, although this is not permitted, or who forms a partnership with him, or who receives [an animal] from him to look after or who gives [his donkey] to him to look after, is exempt from the [law of the] bekhor, for it says: [“I sanctified to me all the firstborn] in Israel,” (Numbers 3:13) but not in non-Jews. In order for a Jew to be liable to redeem the first-born of a donkey, a non-Jew cannot have any ownership or partial ownership over the donkey. So if a Jew buys a fetus (assumedly he buys a pregnant donkey) from a non-Jew it is exempt from the laws of the first-born, because it was conceived under non-Jewish ownership. Similarly, if he sells the fetus to the non-Jew, it is exempt. The mishnah notes that selling a donkey to a non-Jew is not permitted because it is forbidden to sell a large animal to a non-Jew (see Avodah Zarah 1:6). Nevertheless, if one does sell the donkey, it is exempt. If a Jew and a non-Jew are partners in owning a donkey it is exempt. If a Jew receives a donkey to take care of, and in return he keeps some of the offspring, or if he gives the donkey to the non-Jew to take care of and the non-Jew keeps some of the offspring, in both of these cases, the donkey is exempt because the non-Jew has some level of ownership over the animal. The exemption of non-Jews from these laws is derived from the word “in Israel,” which means that the law of the bekhor applies only to animals fully owned by Israelites.

והמשתתף לו – even if the portion of the heathen is substantial and known, as for example, the [yet unborn] firstborn’s arm or leg, or that of its mother. Any time that if they would sever from it that limb, the animal remains with a blemish – this is the partnership of the heathen and it is exempt [from redemption].

Priests and levites are exempt through [an argument made by a] kal vehomer: if they exempted the first-born belonging to the Israelites in the wilderness, it follows all the more so that they should exempt their own. In Numbers 3:45 God instructs Moses to take the Levites in place of the first-born and to take the cattle of the Levites in place of the cattle of the first-born. From here the mishnah derives a kal vehomer (a fortiori) argument. If the Levites exempted the cattle of the first-born in the desert, then their own first-born animals are all the more so exempt from the law of the bekhor. Thus animals owned by priests and Levites are exempt from these laws. As we shall see, the same holds for children of priests and Levites.

והמקבל ממנו – that the female donkey belongs to the heathen that an Israelite receives and takes care of it in order that they will divide its offspring, but the body of the animal belongs to the heathen.

פטור מן הבכורה – that fetus that he (i.e., the Israelite) purchased from the heathen or that he sold to the heathen is not holy, for since the heathen has a portion in it or in its mother, as it states (Numbers 3:13): “I consecrated every first-born in Israel, [man and beast, to Myself, to be Mine],” but not of the heathen.

אם פטרו את של ישראל במדבר – the Levites did not exempt the animals of the Israel in the wilderness, that the first-born of the cattle, [the] cattle [of the Levites] replaced [and redeemed] it, as it is written (Numbers 3: 45): “and the cattle of the Levites in place of their cattle,” but rather, this is how it should be read: The Levities released/served as ransom the holiness of the first born of the Israelites in the wilderness, as it is written (Numbers 3:45): “Take the Levites in place of all the first-born among the Israelite people, [and the cattle of the Levites in place of their cattle; and the Levites shall be Mine, the LORD’s],” but if the sanctity of the Levites released/ransomed the sanctity of the Israelites, it is a law that they would release/ransom themselves. But after we learned that the sanctity of the first-born was released/ransomed from the livestock of the Levities, we learned that the released/ransomed of their donkeys are exempt from [the rules governing] the first-born, as it is written (Numbers 18:15): “but you shall have the first-born of man redeemed, and you shall also have the firstling of impure animals redeemed,” all that the first-born of man has, the first-born of impure animals have, and all that the first-born of man doesn’t have, is not found in the first-born of impure animals. But from the first born of pure animals, the Priests and Levites were not exempt, as we learn ahead.