Midrasz do Kapłańska 4:24

6) (Vayikra 4:24): ("It is a) sin-offering": All of its services must be intended for a "sin-offering." "It (is a sin-offering"): to exclude (from kashruth) an animal that is not slaughtered as such.

10) "And he slaughter it in the place where the burnt-offering is slaughtered." Where is the burnt-offering slaughtered? In the north. This, too, is slaughtered in the north. But do I derive this from here? Is it not already written (Vayikra 6:18): "In the place where the burnt-offering is slaughtered, there shall the sin-offering be slaughtered, before the L–rd"? Why, then, is this specified here? To make it categorical — that if it were not slaughtered in the north, it is pasul.

13) "sin-offering": All of its services must be intended for a sin-offering. "It": to exclude its being slaughtered without intent (for a sin-offering).