Numbers 8:16-18

New Catholic Bible

¹⁶ They are to be wholly dedicated to me from among the people of Israel. I have reserved them for myself as a substitute for all those who open the womb, the firstborn of the people of Israel. ¹⁷ All the firstborn of the people of Israel belong to me, both human and animal. I sanctified them to myself on the day that I killed every firstborn in the land of Egypt. ¹⁸ But I have taken the Levites as a substitute for all the firstborn of the people of Israel.