“Yahweh spoke to Moses. ‘You shall make a bronze basin with a bronze stand for washing. You shall put it between the tent of meeting and the altar, and you shall put water in it. With the water, Aaron and his sons shall wash their hands and their feet. When they go into the tent of meeting, or when they come near the altar to minister, to make an offering by fire to Yahweh, they shall wash with water, so that they may not die. They shall wash their hands and their feet, so that they may not die. It shall be a perpetual ordinance for them, for him, and for his descendants throughout their generations.’”
Once again it is Yahweh who speaks to Moses to tell him exactly how things are to be done. There shall be a bronze basin with a bronze stand for washing. Aaron and his sons will wash their hands and feet when they go into the meeting tent or the altar, so that they would not die. This is a pretty tough penalty for not washing your hands and feet, death. Once again this is a perpetual ordinance.