Leviticus 16:1-2

New King James Version

The Day of Atonement

16 Now the Lord spoke to Moses after ^(A)the death of the two sons of Aaron, when they offered profane fire before the Lord, and died; ² and the Lord said to Moses: “Tell Aaron your brother ^(B)not to come at just any time into the Holy Place inside the veil, before the mercy seat which is on the ark, lest he die; for ^(C)I will appear in the cloud above the mercy seat.