Bamidbar 1:3-5

Orthodox Jewish Bible

³ From twenty years old and upward, all that are ablebodied to serve in tzava b’Yisroel (army in Yisroel); thou and Aharon shall number them by their tzva’ot (legions).

⁴ And with you there shall be a man of every tribe; every one Rosh of the bais of his Avot.

⁵ And these are the shemot haanashim that shall stand with you: of the tribe of Reuven, Elitzur ben Shedeur;