Numbers 1:19-21

Darby Translation

¹⁹ As Jehovah had commanded Moses, so he numbered them in the wilderness of Sinai.

²⁰ And the sons of Reuben, Israel's eldest son, their generations, after their families, according to their fathers' houses, by the number of the names, according to their polls, every male from twenty years old and upward, all that went forth to military service:

²¹ those that were numbered of them, of the tribe of Reuben, were forty-six thousand five hundred.