Exodus 30:18-21

18“Make a bronze basin, with its bronze stand, for washing. 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 feet with water from it. 20Whenever they enter the tent of meeting, they shall wash with water so that they will not die. Also, when they approach the altar to minister by presenting a food offering to the Lord, 21they shall wash their hands and feet so that they will not die. This is to be a lasting ordinance for Aaron and his descendants for the generations to come.”