Numbers 1:19-21

American Standard Version

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

²⁰ And the children of Reuben, Israel’s first-born, their generations, by their families, by their fathers’ houses, according to the number of the names, by their polls, every male from twenty years old and upward, all that were able to go forth to war; ²¹ those that were numbered of them, of the tribe of Reuben, were forty and six thousand and five hundred.