Numbers 3:41-45

And you shall take the Levites for me—I am the LORD—instead of all the firstborn among the people of Israel, and the cattle of the Levites instead of all the firstborn among the cattle of the people of Israel.” So Moses listed all the firstborn among the people of Israel, as the LORD commanded him. And all the firstborn males, according to the number of names, from a month old and upward as listed were 22,273. And the LORD spoke to Moses, saying, “Take the Levites instead of all the firstborn among the people of Israel, and the cattle of the Levites instead of their cattle. The Levites shall be mine: I am the LORD.