Exodus 30:17-21

Then the LORD said to Moses, “Make a bronze washbasin with a bronze stand. Place it between the Tabernacle and the altar, and fill it with water. Aaron and his sons will wash their hands and feet there. They must wash with water whenever they go into the Tabernacle to appear before the LORD and when they approach the altar to burn up their special gifts to the LORD—or they will die! They must always wash their hands and feet, or they will die. This is a permanent law for Aaron and his descendants, to be observed from generation to generation.”