Numbers 3:41-45

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