Halakhah su Deuteronomio 12:15

From the laws of the commandment: Rambam, may his memory be blessed, wrote (Mishneh Torah, Laws of Firstlings 1:17), "Just as the first-born cannot be redeemed, so too can the priest not sell it while it is still unblemished. As since it stands to be offered as a sacrifice, the priest does not have the right to sell it. But at this time (when there is no Temple), since it is destined to be eaten, behold, it is permitted to sell it, even though it is unblemished - whether to a priest or an Israelite." To here [are his words]. Certainly about that which our Teacher, may his memory be blessed, said that it is destined to be eaten, his intention was to say, when it gets a blemish. And a blemished first-born can be sold by the priest at any time, whether the Temple [is standing] or whether the Temple [is not standing], whether it is alive or whether it is slaughtered, to any person, even a non-Jew, as it is completely non-sacred, as it is written (Deuteronomy 12:15), "The pure and the impure together, like the gazelle and the deer." Still, the Sages warned not to sell it in the marketplace in public, but rather at home. The rest of its details are elucidated in Tractate Bekhorot [Chapter 5] (see Tur, Yoreh Deah 306).

To redeem consecrated things upon which a blemish developed: That we were commanded to redeem consecrated [animals] upon which a blemish developed and purchase another animal with their money for a sacrifice. And after the redemption, they go out to being non-sacred and the owners slaughter them and eat them like completely non-sacred [animals]. And about this is it stated, "But in all that your soul desires, you may slaughter and eat meat, etc. the impure and the pure may eat of it, like the gazelle and the deer." After the section mentioned the pure sacrifices and obligated us to sacrifice them "only in the place that the Lord will choose," it stated afterwards about the sacrifices themselves that if a blemish developed in them, that we redeem them and eat them 'in all that our souls desire'; meaning to say that we do with them any of our desires - like the gazelle and the deer, whose body is never holy. And so the traditional explanation came about it that this verse is only speaking about disqualified consecrated [animals] that they be redeemed.