Numbers 1:16-20

These were the men chosen from the Israelite community. They were the leaders of their fathers' tribes; the heads of the families of Israel.

Moses and Aaron summoned these men who had been selected by name.

They had all the Israelites gather together on the first day of the second month, and recorded the people's genealogy according to their tribe and family, and counted up the names of all those aged twenty or older,

as the Lord had told Moses to do. Moses conducted this census in the Sinai desert.

The descendants of Reuben, (he was Israel's firstborn son), men aged twenty or over, were recorded by name according to the genealogical records of their tribe and families. All those registered who could serve in the army