Exodus 28:35
The robe must be worn by Aaron whenever he ministers, and its sound will be heard when he enters the sanctuary before the Lord and when he exits, so that he does not die.
Leviticus 16:2
The Lord said to Moses: “Tell your brother Aaron that he may not come whenever he wants into the holy place
Hebrews 9:12
He entered the most holy place once for all, not by the blood of goats and calves, but by His own blood, having obtained eternal redemption.