16 But I also gave part of Gilead to the tribes of Reuben and Gad. The area I gave them extended from the middle of the Arnon Gorge in the south to the Jabbok River on the Ammonite frontier.

Matthew Henry's Commentary on Deuteronomy 3:16

Commentary on Deuteronomy 3:12-20

(Read Deuteronomy 3:12-20)

This country was settled on the Reubenites, Gadites, and half the tribe of Manasseh: see Numbers 32. Moses repeats the condition of the grant to which they agreed. When at rest, we should desire to see our brethren at rest too, and should be ready to do what we can towards it; for we are not born for ourselves, but are members one of another.