Exodus 30:15

“When you take a census of the children of Israel, according to those who are counted among them, then each man shall give a ransom for his soul to the LORD when you count them, that there be no plague among them when you count them.

They shall give this, everyone who passes over to those who are counted, half a shekel according to the shekel of the sanctuary (the shekel is twenty gerahs); half a shekel for an offering to the LORD.

Everyone who passes over to those who are counted, from twenty years old and upward, shall give the offering to the LORD.

You shall take the atonement money from the children of Israel, and shall appoint it for the service of the Tent of Meeting; that it may be a memorial for the children of Israel before the LORD, to make atonement for your souls.”

The LORD spoke to Moses, saying,

“You shall also make a basin of bronze, and its base of bronze, in which to wash. You shall put it between the Tent of Meeting and the altar, and you shall put water in it.