Exodus 27:21

27:21 In the tent of meeting outside the curtain that is before the testimony, Aaron and his sons are to arrange it from evening to morning before the Lord. This is to be a lasting ordinance among the Israelites for generations to come.

Exodus 28:30

28:30 “You are to put the Urim and the Thummim into the breastpiece of decision; and they are to be over Aaron’s heart when he goes in before the Lord. Aaron is to bear the decisions of the Israelites over his heart before the Lord continually.

Exodus 33:19

33:19 And the Lord said, “I will make all my goodness pass before your face, and I will proclaim the Lord by name before you; I will be gracious to whom I will be gracious, I will show mercy to whom I will show mercy.”