In exchange for land on the eastern side of the Jordan River, Moses commanded Reuben, Gad, and the half-tribe of Manasseh to fight together with their fellow Israelites for the land west of the Jordan (Numbers 32:28–32; Deuteronomy 3:18–20). They committed themselves to this task even after the death of Moses (see Joshua 1:12–18).
2 and said to them, “You have kept all that Moses the servant of the LORD commanded you and have obeyed my voice in all that I have commanded you.