Numbers 1:2-6

²Take ye the sum of all the congregation of the children of Israel, after their families by the house of their fathers, with the number of their names, every male by their poll:

³From twenty years old and upward, all that are able to go forth to war in Israel; thou and Aaron shall number them by their armies.

⁴And with you there shall be a man of every tribe; every one head of the house of his fathers.

⁵And these are the names of the men that shall stand with you: Of the tribe of Reuben; Elizur the son of Shedeur.

⁶Of Simeon; Shelumiel the son of Zurishaddai.