Numbers 3:40-42

New Revised Standard Version, Anglicised Catholic Edition

The Redemption of the Firstborn

⁴⁰ Then the Lord said to Moses: Enrol all the firstborn males of the Israelites, from a month old and upwards, and count their names. ⁴¹ But you shall accept the Levites for me—I am the Lord—as substitutes for all the firstborn among the Israelites, and the livestock of the Levites as substitutes for all the firstborn among the livestock of the Israelites. ⁴² So Moses enrolled all the firstborn among the Israelites, as the Lord commanded him.