While Israel lived in Heshbon and its towns, and in Aroer and its towns, and in all the cities that are along by the side of the Arnon, three hundred years; why didn't you recover them within that time?
Second, he emphasized the fact that Yahweh had given Israel this land. Thus it would have been wrong theologically to allow the Ammonites to take it from them (Judges 11:23-25).