Numbers 1:16-19

These are the chosen leaders of the community, the leaders of their ancestral tribes, the heads of the clans of Israel.” So Moses and Aaron called together these chosen leaders, and they assembled the whole community of Israel on that very day. All the people were registered according to their ancestry by their clans and families. The men of Israel who were twenty years old or older were listed one by one, just as the LORD had commanded Moses. So Moses recorded their names in the wilderness of Sinai.