Exodus 30:18-20

18Thou shalt also make a laver of copper, and its stand of copper, for washing; and thou shalt put it between the tent of meeting and the altar, and shalt put water in it.

19And Aaron and his sons shall wash their hands and their feet out of it.

20When they go into the tent of meeting, they shall wash with water, that they may not die; or when they come near to the altar to serve, to burn an offering by fire to Jehovah.