35 And it shall be upon Aaron, to minister: and his sound shall be heard when he goeth in to the holy place before the LORD, and when he cometh out; that he may not die.
Exodus 28:35 Cross References - Webster
Leviticus 16:2
2 And the LORD said to Moses, Speak to Aaron thy brother, that he come not at all times into the holy place within the vail, before the mercy-seat, which is upon the ark; that he may not die: for I will appear in the cloud upon the mercy-seat.
Hebrews 9:12
12 Neither by the blood of goats and calves, but by his own blood; he entered in once into the holy place, having obtained eternal redemption for us.