Numbers 1:2-4

New Revised Standard Version Catholic Edition

² Take a census of the whole congregation of Israelites, in their clans, by ancestral houses, according to the number of names, every male individually; ³ from twenty years old and upward, everyone in Israel able to go to war. You and Aaron shall enroll them, company by company. ⁴ A man from each tribe shall be with you, each man the head of his ancestral house.