Exodus 28:35

28:35 The robe is to be on Aaron as he ministers, and his sound will be heard when he enters the Holy Place before the Lord and when he leaves, so that he does not die.

Exodus 34:34

34:34 But when Moses went in before the Lord to speak with him, he would remove the veil until he came out. Then he would come out and tell the Israelites what he had been commanded.