Exodus 30:17-21 NLT

17 And the LORD said to Moses,
18 "Make a large bronze washbasin with a bronze pedestal. Put it between the Tabernacle and the altar, and fill it with water.
19 Aaron and his sons will wash their hands and feet there
20 before they go into the Tabernacle to appear before the LORD and before they approach the altar to burn offerings to the LORD. They must always wash before ministering in these ways, or they will die.
21 This is a permanent law for Aaron and his descendants, to be kept from generation to generation."