Leviticus 16:2

16:2 and the Lord said to Moses: “Tell Aaron your brother that he must not enter at any time into the holy place inside the veil-canopy in front of the atonement plate that is on the ark so that he may not die, for I will appear in the cloud over the atonement plate.

Leviticus 22:2

22:2 “Tell Aaron and his sons that they must deal respectfully with the holy offerings of the Israelites, which they consecrate to me, so that they do not profane my holy name. I am the Lord.