Numbers 3:44-46

New Revised Standard Version, Anglicised

⁴⁴ Then the Lord spoke to Moses, saying: ⁴⁵ Accept the Levites as substitutes for all the firstborn among the Israelites, and the livestock of the Levites as substitutes for their livestock; and the Levites shall be mine. I am the Lord. ⁴⁶ As the price of redemption of the two hundred and seventy-three of the firstborn of the Israelites, over and above the number of the Levites,