Numbers 3:41-45

You shall take the Levites for Me, I am the LORD, instead of all the firstborn among the sons of Israel, and the cattle of the Levites instead of all the firstborn among the cattle of the sons of Israel.” So Moses numbered all the firstborn among the sons of Israel, just as the LORD had commanded him; and all the firstborn males by the number of names from a month old and upward, for their numbered men were 22,273. Then the LORD spoke to Moses, saying, “Take the Levites instead of all the firstborn among the sons of Israel and the cattle of the Levites. And the Levites shall be Mine; I am the LORD.