Leviticus 16:1-2

Wycliffe Bible

16 And the Lord spake to Moses, after the death of the two sons of Aaron, when they offered alien fire (when they offered unholy fire), and were slain,

² and commanded to him and said, Speak thou to Aaron, thy brother, that he enter not in all time into the saintuary, which is within the veil before the propitiatory, with which the ark is covered, that he die not; for I shall appear in a cloud on God’s answering place; (and commanded to him and said, Tell thou thy brother Aaron, that he must not enter into the sanctuary, which is behind the Veil, to go before the propitiatory, that is, the mercy seat, or the lid, which is on the Ark, that is, the Box for the tablets of the Law, except at the appointed time, so that he not die; for I shall appear there in a cloud above the propitiatory, or God’s answering place;)