Leviticus 6:17-18

It shall not be baken with leaven. I have given it unto them for their portion of my offerings made by fire; it is most holy, as is the sin offering, and as the trespass offering. All the males among the children of Aaron shall eat of it. It shall be a statute for ever in your generations concerning the offerings of the LORD made by fire: every one that toucheth them shall be holy.