Leviticus 6:17; Leviticus 6:25

17 It shall not be baked with leaven. I have given it as their portion of my food offerings. It is a thing most holy, like the sin offering and the guilt offering.

25 "Speak to Aaron and his sons, saying, This is the law of the sin offering. In the place where the burnt offering is killed shall the sin offering be killed before the LORD; it is most holy.