Numbers 1:19-21

New Century Version

¹⁹ Moses did exactly what the Lord had commanded and listed the people while they were in the Desert of Sinai.

²⁰ The tribe of Reuben, the first son born to Israel, was counted; all the men twenty years old or older who were able to serve in the army were listed by name with their families and family groups. ²¹ The tribe of Reuben totaled 46,500 men.