Siman 319

The sages taught in the Mishnah in Chullin (69b): If a first-born animal has difficulty giving birth, one may cut it limb by limb and cast it to the dogs, for as long as the majority of it has not emerged, it is not sanctified (Rashi). If the majority of it emerged at once and he cut it (ibid.), this must be buried and she is exempt from the law of the firstborn. The reason it must be buried is because upon the emergence of the majority, sanctity takes effect upon it, as we apply to it "that which is born." And she is exempt from the law of the firstborn because that which follows it is not a firstborn, whether the first emerged limb by limb or whether the majority emerged at once, for the second is not a "peter rechem" (ibid.). That which he cuts from the majority onwards requires burial, but what he cut limb by limb until its majority does not require burial even when they are before us; however, from its majority onwards it requires burial even if the previous parts were cast to the dogs (Tosafot ibid. 70a). The general rule of the matter is that we do not say that after the majority of the fetus was gathered through the cutting of the limbs, all the limbs shall be sanctified retroactively such that if they are before us they would require burial; we do not say so, for we hold that it is sanctified from this point forward and not retroactively. And in the Gemara there, there is a dispute regarding this, see there.

The Rambam has another approach in this matter, and this is his wording in chapter 4, law 14: A first-time mother who has difficulty giving birth, one may cut that limb and throw it to the dogs, and the one that comes after it is a firstborn; if the majority of it emerged, it must be buried and she is exempt from the law of the firstborn. And if he cut a limb and left it, a limb and left it, until its majority was completed, then all the limbs require burial and she is exempt from the law of the firstborn; since its majority emerged, whether whole or in pieces, and they are before us, it is sanctified retroactively. Thus far his words. And he disagrees on two points: the first, that if he fed it to the dogs piece by piece, she is not exempt from the law of the firstborn, for since it is not considered as born, it does not open the womb, and the one that comes after it is a firstborn. And the second, that if the limbs are before us when its majority emerged, the limbs are sanctified retroactively, for he ruled like the one who holds in the Gemara that it is sanctified retroactively. And the first opinion is the view of Rashi, Tosafot, the Rash, and the Tur, and in the Shulchan Aruch both opinions were brought; see there.

If a third of the fetus emerged and one sold it to a gentile while it was not yet sanctified, and afterwards another third emerged—according to the Rambam, for whom it is sanctified retroactively, the first third also became sanctified, and it is forbidden to give it to a gentile. For only a blemished bechor is permitted even to a gentile, as it is written, "as the gazelle and as the hart," but not an unblemished bechor. Even if it became a tereifah, we do not read concerning it "as the gazelle and as the hart," since it is a tereifah and is forbidden to an Israelite, and it is not similar to a gazelle and a hart; consequently, its law is like an unblemished bechor, and it is forbidden for benefit and requires burial. But according to Rashi, the Tosafot, and the Rosh, for whom it is sanctified from this point forward, the first third remains in its permitted state and is not sanctified. And similarly, if the first third emerged via a caesarean section, which has no sanctity of a bechor, and two-thirds emerged via the womb, and the sanctity takes effect upon it at the middle third—which constitutes the majority of the offspring—according to the Rambam, for whom we follow the retroactive principle, it is not sanctified. For from the majority that was fit to be sanctified, the primary part emerged via a caesarean section, such that when the majority was completed—meaning slightly more than half—the majority of this majority was via a caesarean section. But according to Rashi, the Tosafot, and the Rosh, the first third is not taken into account at all, and behold, two-thirds emerged via the womb and it is sanctified as a bechor.

If the majority of the fetus emerged, and within this majority there is a minority of a limb whose majority is inside, and if we were to join this minority to its majority that is inside there would not be a majority outside, nevertheless it is considered born. We cast the minority of the limb toward that which is outside and not toward that which is inside, and it is forbidden to sell it to a gentile and forbidden in all benefits, and it exempts the one that follows it from the status of firstborn. The reason is that we do not leave the majority of the animal to follow the majority of a limb, and we wrote similarly above in siman 14, see there. However, if half of the fetus emerged, and within this half there is a majority of one of any limb, in a manner that when we join to the majority of this limb its minority that is inside it would constitute a majority of the fetus, this was an inquiry in the Gemara: whether we join the minority that is inside to that which is outside or not. Therefore, this is a doubt, and it is forbidden to sell it to a gentile and forbidden in other benefits. The Rambam wrote that the one that follows it is a doubtful firstborn, see there, and the Tur wrote likewise. Their intention is when its second half did not emerge via the womb but rather via the side, for if the second half also emerged via the womb, why would the one that follows it be a doubtful firstborn? For even according to the Rambam, like the pieces before us, it exempts the one that follows it (see Shach, and it requires further study. And one must say that what he wrote in subsection 12, "and it deals with where he cut etc.," his intention was that he fed it to dogs; but how is it possible to say so, for it is forbidden in benefit? Rather, it is certainly as I wrote. And see the Gilyon HaMaharsha who wrote that this which is sanctified retroactively applies specifically to what emerged outside and not what is inside, and therefore it is permitted to inflict a blemish on a firstborn while it is still inside. And the Maharsha wrote likewise there. He further wrote that if it is not a non-viable birth, it is forbidden to cut a limb, as it is called inflicting a blemish on consecrated items since it is sanctified retroactively; but this is not implied in Tosafot in the sugya there, see there and delve into it).