[If] one sets aside a [lamb for] redemption of a firstborn donkey, and it dies —- R’ Eliezer says: One is responsible for it, as with the five selaim of the son. The Sages, however, say: One is not responsible for it, as with the redemption of maaser sheni. R’ Yehoshua and R’ Tzadok testified concerning the redemption of a firstborn donkey that died, that there is nothing here for a Kohen.  If the firstborn donkey dies —- R’ Eliezer says: It must be buried, and benefit may be derived from the lamb. The Sages, however, say: It need not be buried, and the lamb belongs to a Kohen.

[If] he does not wish to redeem it, he must decapitate it with a large knife from behind and bury it.  The precept of redemption takes precedence over the precept of decapitation, as it states (Ex. 13:13): And if you do not redeem it, you shall decapitate it. The precept of yiud takes precedence over the precept of redemption, as it states (Ex. 21:8): Who did not designate her, he shall cause her to be redeemed.  The precept of yibum takes precedence over the precept of chalitzah —- in the early days, when they would intend [to perform yibum] for the sake of [fulfilling] the precept; but now that they do not intend [to perform yibum] for the sake of [fulfilling] the precept, they said: The precept of chalitzah takes precedence over the precept of yibum.  The precept of redemption is on the owner. He takes precedence over any other person, as it is said (Lev. 27:27): “And if it is not redeemed, it shall be sold for its valuation.”