Numbers 1:19-21

International Standard Version

¹⁹ just as the Lord had commanded Moses. He numbered them in the Sinai desert.

Numbering the Tribes

²⁰ The genealogies of the descendants of Reuben, the firstborn of Israel, were recorded individually, according to their tribes and ancestral houses, as were the names of all the men 20 years and above who could serve in the army. ²¹ Those registered with the tribe of Reuben numbered 46,500.