Numbers 1:17-19

Young's Literal Translation

¹⁷ And Moses taketh -- Aaron also -- these men, who were defined by name,

¹⁸ and all the company they assembled on the first of the second month, and they declare their births, by their families, by the house of their fathers, in the number of names from a son of twenty years and upward, by their polls,

¹⁹ as Jehovah hath commanded Moses; and he numbereth them in the wilderness of Sinai.