Leviticus 16:1-2

Revised Standard Version

The Day of Atonement

16 The Lord spoke to Moses, after the death of the two sons of Aaron, when they drew near before the Lord and died; ² and the Lord said to Moses, “Tell Aaron your brother not to come at all times into the holy place within the veil, before the mercy seat which is upon the ark, lest he die; for I will appear in the cloud upon the mercy seat.