Numbers 3:40-42

Young's Literal Translation

⁴⁰ And Jehovah saith unto Moses, `Number every first-born male of the sons of Israel from a son of a month and upward, and take up the number of their names;

⁴¹ and thou hast taken the Levites for Me (I [am] Jehovah), instead of every first-born among the sons of Israel, and the cattle of the Levites instead of every firstling among the cattle of the sons of Israel.'

⁴² And Moses numbereth, as Jehovah hath commanded him, all the first-born among the sons of Israel.