And this is a simple matter in the sight of the Lord; He will also deliver the Moabites into your hand. 2 Kings 3:18
Moab revolts: 3:1-27. Moab has ceased to pay the tribute imposed in the time of Omri. So Joram, with Jehoshaphat of Judah, invades. The invasion force tries to cross the desert to surprise the enemy. After 7 days, they run out of water and are near death. Elisha, honoring the godly king Jehoshaphat, seeks God’s guidance. The water needed is provided, and victory over Moab’s army follows. However, the combined forces retreat after the king of Moab sacrifices his son. This reaction to human sacrifice is not explained in the OT test or by archaeological finds.
An inscription on what is known as the Moabite Stone tallies with the biblical account. It tells us that in spite of this military victory, the Moabites were not returned to tributary status.
Jehoram, King of Israel
2 And he did evil in the sight of the Lord, but not like his father and mother; for he put away the sacred pillar of Baal that his father had made. 3 Nevertheless he persisted in the sins of Jeroboam the son of Nebat, who had made Israel sin; he did not depart from them.
Elisha Predicts Victory over Moab
17 For thus says the Lord: ‘You shall not see wind, nor shall you see rain; yet that valley shall be filled with water, so that you, your cattle, and your animals may drink.’ 18 And this is a simple matter in the sight of the Lord; He will also deliver the Moabites into your hand. 19 Also you shall attack every fortified city and every choice city, and shall cut down every good tree, and stop up every spring of water, and ruin every good piece of land with stones.”
–> Because of Jehoshahat, king of Judah who sought counsel from a prophet of the Lord, God fought against Moab (Mesha, king of Moab). Both Jehoshaphat and Elisha were minority in number among many evil kings and false prophets. What counts is how they were perceived by God.