Numbers 1:16-18

¹⁶These are those called of the company, princes of the tribes of their fathers; they are heads of the thousands of Israel.

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

¹⁸and 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,