תלמוד על תמורה 3:1

Naḥman, the son of Rebbi Samuel bar Naḥmani in the name of Rebbi Samuel bar Naḥmani: The five kinds of purification sacrifices which are left to die, if the Court decides to abolish, they may abolish³⁴⁶Mishnah Temurah 3:1. A purification sacrifice is an obligation; it cannot be offered voluntarily nor can there be more than one sacrifice for one obligation. Also it is most holy; its sacred status cannot be abolished. Therefore the calf born to an animal dedicated as purification sacrifice, or a substitute for such an animal, or one whose owner had died, or a dedicated one which became too old to be sacrificed, or one which was lost and found later when it had developed a defect and the owner in the meantime had offered a substitute, are intrinsically holy but forbidden as sacrifices. The rule, classified in the Babli (Bekhorot 16a, Temurah 18a) as “tradition”, i. e., being part of the original institutions of post-exilic Judaism, possibly older, is treated here as rabbinic interpretation.. Rebbi Ḥiyya bar Ada said, that means that they are not sent to die but are used for voluntary sacrifices. But as far as sacrificing on the altar is concerned, no purification sacrifice destined to die may be sacrificed³⁴⁷While biblically the animal cannot become a sacrifice in any form, if it develops a blemish it can be sold as profane and the money used for additional Temple sacrifices..