Midrash su Deuteronomio 14:3

He brought forth from the earth all kinds of abominations and creeping things, all of them are unclean. Such (creatures) which have been created from the earth, their life (or soul) and body are from the earth, and when they return they touch their dust at the place whence they were created, as it is said, "Thou takest away their breath, they die, and return to their dust" (Ps. 104:29); and it is written, "And the spirit of the beast goes downward to the earth" (Eccles. 3:21).

(Devarim 14:3) "You shall not eat any abomination": R. Eliezer says: Whence is it derived that if one slit the ear of a bechor (a first-born beast, thus blemishing it) and ate of it (the beast, after slaughtering it), he transgresses a negative commandment? From "You shall not eat any abomination."