Exodus 30:18-20

18“You will also make a basin of bronze with a bronze stand for washing. You are to place it between the Tent of Meeting and the altar and put water in it.

19Aaron and his sons are to wash their hands and their feet there.

20Whenever they go into the Tent of Meeting or come near to the altar to minister, to present an offering made by fire in smoke to Adonai, they are to wash with water so that they do not die.