A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
4 Kings (2 Kings) 3:1
kg2 3:1JEHORAM'S EVIL REIGN OVER ISRAEL. (Kg2 3:1-3)
Jehoram the son of Ahab began to reign over Israel in Samaria the eighteenth year of Jehoshaphat--(compare Kg1 22:51). To reconcile the statements in the two passages, we must suppose that Ahaziah, having reigned during the seventeenth and the greater part of the eighteenth year of Jehoshaphat, was succeeded by his brother Joram or Jehoram, in the end of that eighteenth year, or else that Ahaziah, having reigned two years in conjunction with his father, died at the end of that period when Jehoram ascended the throne. His policy was as hostile as that of his predecessors to the true religion; but he made some changes. Whatever was his motive for this alteration--whether dread of the many alarming judgments the patronage of idolatry had brought upon his father; or whether it was made as a small concession to the feelings of Jehoshaphat, his ally, he abolished idolatry in its gross form and restored the symbolic worship of God, which the kings of Israel, from the time of Jeroboam, had set up as a partition wall between their subjects and those of Judah.
4 Kings (2 Kings) 3:4
kg2 3:4MESHA, KING OF MOAB, REBELS. (Kg2 3:4-5)
Mesha king of Moab, &c.--As his dominions embraced an extensive pasture country, he paid, as annual tribute, the wool of a hundred thousand lambs and a hundred thousand rams. It is still common in the East to pay custom and taxes in the fruits or natural produce of the land.
4 Kings (2 Kings) 3:5
kg2 3:5king of Moab rebelled--This is a repetition of Kg2 1:1, in order to introduce an account of the confederate expedition for crushing this revolt, which had been allowed to continue unchecked during the short reign of Ahaziah.
4 Kings (2 Kings) 3:6
kg2 3:6ELISHA PROMISES WATER AND VICTORY OVER MOAB. (2Ki. 3:6-24)
King Jehoram . . . numbered Israel--made a levy from his own subjects, and at the same time sought an alliance with Jehoshaphat, which, as on the former occasion with Ahab, was readily promised (Kg1 22:4).
4 Kings (2 Kings) 3:8
kg2 3:8Which way shall we go up? And he answered, The way through the wilderness of Edom--This was a long and circuitous route, by the southern bend of the Dead Sea. Jehoshaphat however preferred it, partly because the part of the Moabite territory at which they would arrive, was the most defenseless; and partly because he would thereby enlist, in the expedition, the forces of the king of Edom. But, in penetrating the deep, rocky valley of Ahsy, which forms the boundary between Edom and Moab, the confederate army was reduced, both man and beast, to the greatest extremities for want of water. They were disappointed by finding the wady of this valley, the brook Zered (Deu 2:13-18) [ROBINSON], dry. Jehoram was in despair. But the pious mind of Jehoshaphat inquired for a prophet of the Lord; and, on being informed that Elisha was at hand, the three kings "went down to him"; that is, to his tent, which was either in the camp, or close by it. He had been directed thither by the Spirit of God for this special purpose. They went to him, not only as a mark of respect, but to supplicate for his assistance.
4 Kings (2 Kings) 3:11
kg2 3:11which poured water on the hands of Elijah--that is, was his servant--this being one of the common offices of a servant. The phrase is used here as synonymous with "a true and eminent prophet," who will reveal God's will to us.
4 Kings (2 Kings) 3:13
kg2 3:13What have I to do with thee? &c.--Wishing to produce a deep spirit of humility and contrition, Elisha gave a stern repulse to the king of Israel, accompanied by a sarcastic sneer, in bidding him go and consult Baal and his soothsayers. But the distressed condition, especially the imploring language, of the royal suppliants, who acknowledged the hand of the Lord in this distress, drew from the prophet the solemn assurance, that solely out of respect to Jehoshaphat, the Lord's true servant, did he take any interest in Jehoram.
4 Kings (2 Kings) 3:15
kg2 3:15bring me a minstrel--The effect of music in soothing the mind is much regarded in the East; and it appears that the ancient prophets, before entering their work, commonly resorted to it, as a preparative, by praise and prayer, to their receiving the prophetic afflatus.
the hand of the Lord--a phrase significantly implying that the gift of prophecy was not a natural or inherent gift, but conferred by the power and grace of God.
4 Kings (2 Kings) 3:16
kg2 3:16Make this valley full of ditches--capable of holding water.
4 Kings (2 Kings) 3:17
kg2 3:17Ye shall not see wind--It is common in the East to speak of seeing wind, from the clouds of straw, dust, or sand, that are often whirled into the air, after a long drought.
4 Kings (2 Kings) 3:20
kg2 3:20when the meat offering was offered--that is, at the time of the morning sacrifice, accompanied, doubtless, with solemn prayers; and these led, it may be, by Elisha on this occasion, as on a similar one by Elijah (Kg1 18:36).
behold, there came water by the way of Edom--Far from the Israelitish camp, in the eastern mountains of Edom, a great fall of rain, a kind of cloudburst, took place, by which the wady was at once filled, but they saw neither the wind nor the rains. The divine interposition was shown by introducing the laws of nature to the determined end in the predetermined way [KEIL]. It brought not only aid to the Israelitish army in their distress, by a plentiful supply of water, but destruction on the Moabites, who, perceiving the water, under the refulgent rays of the morning sun, red like blood, concluded the confederate kings had quarrelled and deluged the field with their mutual slaughter; so that, rushing to their camp in full expectation of great spoil, they were met by the Israelites, who, prepared for battle, fought and pursued them. Their country was laid waste in the way, which has always been considered the greatest desolation in the East (Kg2 3:24).
4 Kings (2 Kings) 3:25
kg2 3:25Kir-haraseth--(now Kerak)--Castle of Moab--then, probably, the only fortress in the land.
4 Kings (2 Kings) 3:27
kg2 3:27took his eldest son that should have reigned in his stead, and offered him for a burnt offering, &c.--By this deed of horror, to which the allied army drove the king of Moab, a divine judgment came upon Israel; that is, the besiegers feared the anger of God, which they had incurred by giving occasion to the human sacrifice forbidden in the law (Lev 18:21; Lev 20:3), and hastily raised the siege.