Exodus 30:11-16

The LORD also spoke to Moses, saying, “When you take a census of the sons of Israel to number them, then each one of them shall give a ransom for himself to the LORD, when you number them, so that there will be no plague among them when you number them. This is what everyone who is numbered shall give: half a shekel according to the shekel of the sanctuary (the shekel is twenty gerahs), half a shekel as a contribution to the LORD. Everyone who is numbered, from twenty years old and over, shall give the contribution to the LORD. The rich shall not pay more and the poor shall not pay less than the half shekel, when you give the contribution to the LORD to make atonement for yourselves. You shall take the atonement money from the sons of Israel and shall give it for the service of the tent of meeting, that it may be a memorial for the sons of Israel before the LORD, to make atonement for yourselves.”