Leviticus 9:18-21

18Then Aaron slaughtered the bull and the ram for the people’s peace offering. His sons brought him the blood, and he splattered it against all sides of the altar.

19Then he took the fat of the bull and the ram—the fat of the broad tail and from around the internal organs—along with the kidneys and the long lobes of the livers.

20He placed these fat portions on top of the breasts of these animals and burned them on the altar.

21Aaron then lifted up the breasts and right thighs as a special offering to the Lord, just as Moses had commanded.