Numbers 1:2-4

Darby Translation

² Take the sum of the whole assembly of the children of Israel, after their families, according to their fathers' houses, by the number of the names, every male, according to their polls;

³ from twenty years and upward, all that go forth to military service in Israel: ye shall number them according to their hosts, thou and Aaron.

⁴ And with you there shall be a man for every tribe, a man who is the head of his father's house.