Bechoros 1:6-7

Bechoros 1:6

If a person sets aside a lamb to redeem a firstborn donkey but it dies before giving it to a kohein, Rabbi Eliezer says that he is obligated to replace it, the same as is done with the five sela coins used in a pidyon haben. The Sages, however, say that one is not obligated to replace it, the same as with the redemption of second tithe. Rabbi Yehoshua and Rabbi Tzaddok testified regarding the redemption of a firstborn donkey that died that the kohein receives nothing. If the firstborn donkey itself died (after the lamb to redeem it has been set aside but before it has been delivered), Rabbi Eliezer says that it must be buried and one may derive benefit from the lamb; the Sages say that the donkey need not be buried and the lamb belongs to the kohein (because the redemption is effected when the lamb is separated, not when it’s delivered).

Bechoros 1:7

If the donkey’s owner doesn’t want to redeem it, he must break its neck from behind with an axe and bury it. The mitzvah of redeeming a firstborn donkey takes priority over the mitzvah to break its neck as per Exodus 13:13, “If you don’t redeem it, then you must break its neck.” Similarly, the mitzvah to designate a Jewish maidservant as a wife takes priority over the mitzvah to redeem her as per Exodus 21:8, “if he has not designated her, then he must let her be redeemed.” Likewise, the mitzvah of yibum (levirate marriage) takes priority over the mitzvah of chalitzah (the shoe-removal ceremony). This was the case originally, when the parties involved were motivated by fulfilling the mitzvah of yibum; nowadays, since people want to perform yibum for insincere reasons, the Sages have said that chalitzah takes priority over yibum. The mitzvah to redeem a consecrated animal applies to the animal’s owner. He takes precedence over anyone else who wants to redeem it as per Leviticus 27:27, “If it isn’t redeemed, then it shall be sold based upon the appraisal.”