Exodus 30:19-21

19Aaron and his sons must use the water from the bowl to wash their hands and their feet.

20Every time they go into the Tent of Meeting, they must wash in the same way. Then they will not die. They must also wash before they go to the altar to make a burnt offering to the Lord.

21If they wash their hands and their feet, they will not die as they serve me. This will always be a rule for Aaron and for his descendants, the priests.’