Numbers 1:3-5

Darby Translation

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.

⁵ And these are the names of the men that shall stand with you: for Reuben, Elizur the son of Shedeur;