This is but a small favour in comparison of what he intends to you for Jehoshaphat's sake. He will give you more than you ask or expect. For they were so weakened and discouraged with the great drought, that they had no hopes of proceeding in the offensive war, and thought it sufficient, if it were possible, to defend themselves from the Moabites, 2 Kings 3:13.
Related Commentaries of 2 Kings 3:18
2 Kings 3:18
18 And this is but a light thing in the sight of the LORD: he will deliver the Moabites also into your hand.