Exodus 30:15-19

The rich shall not give more, and the poor shall not give less than half a shekel, when they give an offering unto the LORD, to make an atonement for your souls.

And thou shalt take the atonement money of the children of Israel, and shalt appoint it for the service of the tabernacle of the congregation; that it may be a memorial unto the children of Israel before the LORD, to make an atonement for your souls.

And the LORD spake unto Moses, saying,

Thou shalt also make a laver of brass, and his foot also of brass, to wash withal: and thou shalt put it between the tabernacle of the congregation and the altar, and thou shalt put water therein.

For Aaron and his sons shall wash their hands and their feet thereat: