Numbers 1:19-20

¹⁹as the Lord commanded to Moses, (and so he numbered them there in the Sinai Desert).

²⁰And of Reuben, the first begotten of Israel, were numbered, in the desert of Sinai, by their generations, and families, and houses, and by the names of all the heads, all thing that is of male kind, from twenty years and above, of men going forth to battle, (And so the sons of Reuben, the first-born of Israel, were listed by their generations, and families, and houses of their kindreds, with the names of all who were twenty years of age and older, and all the men who could go forth to battle numbered)