Numbers 1:18-20

New King James Version

¹⁸ and they assembled all the congregation together on the first day of the second month; and they recited their ^(A)ancestry by families, by their fathers’ houses, according to the number of names, from twenty years old and above, each one individually. ¹⁹ As the Lord commanded Moses, so he numbered them in the Wilderness of Sinai.

²⁰ Now the ^(B)children of Reuben, Israel’s oldest son, their genealogies by their families, by their fathers’ house, according to the number of names, every male individually, from twenty years old and above, all who were able to go to war: