Whenever they enter the Tent of Meeting or approach the altar to minister by presenting an offering made by fire to the LORD, they must wash with water so that they will not die.

Exodus 30:19
with which Aaron and his sons are to wash their hands and feet.

Exodus 30:21
Thus they are to wash their hands and feet so that they will not die; this shall be a permanent statute for Aaron and his descendants for the generations to come."

Exodus 40:31
and from it Moses, Aaron, and his sons washed their hands and feet.

Leviticus 8:6
Then Moses presented Aaron and his sons and washed them with water.

Leviticus 16:4
He is to wear the sacred linen tunic, with linen undergarments. He must tie a linen sash around him and put on the linen turban. These are holy garments, and he must bathe himself with water before he wears them.

When they go into the tabernacle of the congregation, they shall wash with water, that they die not; or when they come near to the altar to minister, to burn offering made by fire to the LORD: