Deuteronomy 3:16,17
And to the Reubenites and to the Gadites I gave from Gilead even to the river Arnon half the valley, and the border even to the river Jabbok, which is the border of the children of Ammon;
Torrey's Topical Textbook—AKJV

Joshua 13:15-23
And Moses gave to the tribe of the children of Reuben inheritance according to their families.
Torrey's Topical Textbook—AKJV