Numbers 3:41-45

41And you shall take the Levites for Me—I am the Lord—instead of all the firstborn among the children of Israel, and the livestock of the Levites instead of all the firstborn among the livestock of the children of Israel.”

42So Moses numbered all the firstborn among the children of Israel, as the Lord commanded him.

43And all the firstborn males, according to the number of names from a month old and above, of those who were numbered of them, were twenty-two thousand two hundred and seventy-three.

44Then the Lord spoke to Moses, saying:

45“Take the Levites instead of all the firstborn among the children of Israel, and the livestock of the Levites instead of their livestock. The Levites shall be Mine: I am the Lord.