Leviticus 27:1-3

Again, the LORD spoke to Moses, saying, “Speak to the sons of Israel and say to them, ‘When a man makes a difficult vow, he shall be valued according to your valuation of persons belonging to the LORD. If your valuation is of the male from twenty years even to sixty years old, then your valuation shall be fifty shekels of silver, after the shekel of the sanctuary.