Numbers 1:1-4

Then the LORD spoke to Moses in the wilderness of Sinai, in the tent of meeting, on the first of the second month, in the second year after they had come out of the land of Egypt, saying, “Take a census of all the congregation of the sons of Israel, by their families, by their fathers’ households, according to the number of names, every male, head by head from twenty years old and upward, whoever is able to go out to war in Israel, you and Aaron shall number them by their armies. With you, moreover, there shall be a man of each tribe, each one head of his father’s household.