For it was of Yahweh to harden their hearts, to come against Israel in battle, that he might utterly destroy them, that they might have no favor, but that he might destroy them, as Yahweh commanded Moses.
"Here is a biblical lesson which has always been difficult for the people of God to learn. Deuteronomy commanded Israel to obey God, destroy the inhabitants, have no mercy, make no covenant, make no marriages (Joshua 7:1-3). Such a command had a divine purpose. It removed the temptations to follow other gods. From the days of the Judges and especially from the period of Solomon onward, the great temptation was to make political alliances through covenants and political marriages between royal families (1 Kings 11:1-8; 1 Kings 16:31; 1 Kings 20:30-43). To protect Israel against the major sin of idolatry, God commanded her not to show mercy to the enemy. To enable her to keep his commandment, God caused her enemies to fight her rather than seek mercy and peace." [Note: Butler, p. 130.] 