exodus 30:17-21
17 The Lord spoke to Moses, saying, 18 “You shall also make a laver of bronze, with its base of bronze, for washing; and you shall put it between the tent of meeting and the altar, and you shall put water in it. 19 Aaron and his sons shall wash their hands and their feet from it; 20 when they enter the tent of meeting, they shall wash with water, so that they will not die; or when they approach the altar to minister, by offering up in smoke a fire sacrifice to the Lord. 21 So they shall wash their hands and their feet, so that they will not die; and it shall be a perpetual statute for them, for Aaron and his descendants throughout their generations.”