Adam Clarke on Deuteronomy 13:17

And there shall cleave naught of the cursed thing - As God did not permit them to take the spoils of these idolatrous cities, they could be under no temptation to make war upon them. It could only be done through a merely religious motive, in obedience to the command of God, as they could have no profit by the subversion of such places. How few religious wars would there ever have been in the world had they been regulated by this principle: "Thou shalt neither extend thy territory, nor take any spoils!"