Leviticus 6:16-17

What is left of it Aaron and his sons are to eat. It shall be eaten as unleavened bread in a holy place; they are to eat it in the courtyard of the Tent of Meeting. [1 Cor 9:13, 14] It shall not be baked with leaven [which represents corruption or sin]. I have given it as their share of My offerings by fire; it is most holy, like the sin offering and the guilt offering.