Deuteronomy 3:8

3:8 So at that time we took the land of the two Amorite kings in the Transjordan from Wadi Arnon to Mount Hermon

Deuteronomy 3:16

3:16 To the Reubenites and Gadites I allocated the territory extending from Gilead as far as Wadi Arnon (the exact middle of the wadi was a boundary) all the way to the Wadi Jabbok, the Ammonite border.