Lev Leviticus, chapter Book of Leviticus, chapter 16
And the LORD spoke unto Moses, after the death of the two sons of Aaron, when they drew near before the LORD, and died; Lev 10:1; Num 3:4and the LORD said unto Moses: 'Speak unto Aaron thy brother, that he come not at all times into the holy place within the veil, before the ark-cover which is upon the ark; that he die not; for I appear in the cloud upon the ark-cover. Exo 30:10