And he said: Which way shall we go up? But he answered: By the desert of Edom.

And he saith, 'Where is this, the way we go up?' and he saith, 'The way of the wilderness of Edom.'

And he said, Which way are we to go? And he said in answer, By the waste land of Edom.

And he said, "Along which way shall we ascend?" So he responded, "Along the desert of Idumea."

The readiest and most natural "way" was across the Jordan near Jericho into the Arboth-Moab, and then along the eastern shore of the Dead Sea to Moab proper, the tract south of the Arnon. But the way chosen was that which led to the Edomite country, namely, round the southern extremity of the Dead Sea, and across the Arabah, or continuation of the Jordan and Dead Sea valley. Thus would be effected a junction with the forces of Edom, which had resumed its dependence on Judah, though the year before it had been in alliance with Moab 2-Chronicles 20:22; and they would come upon the Moabites unprepared.

Through the wilderness of Edom - Because he expected the king of Edom to join them, as we find he did; for, being tributary to Judah, he was obliged to do it.

And he said, which way shall we go up.... That is, Jehoram said so to Jehoshaphat, consulting with him which was the best way to take to the land of Moab, whether the shortest way, over Jordan; or some other:
and he answered, the way through the wilderness of Edom; which bordered upon it, and the same through which the Israelites passed; for Kadesh was on the extreme border of Edom, whither they came, Numbers 20:1 and this Jehoshaphat proposed, partly that they might come upon Moab unawares, and attack them where they were weakest, and not on their guard; and partly, to take the king of Edom with them, who was no other than Jehoshaphat's deputy, and so be assisting to them, and prevent him from revolting, which otherwise he might take this opportunity of doing.

Which 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 (Deuteronomy 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.

In reply to Joram's question, "By which way shall we advance (against Moab)?" Jehoshaphat decided in favour of "the way through the desert of Edom." There were two ways by which it was possible to enter the land of the Moabites; namely, either by going above the Dead Sea, and crossing the Jordan and the boundary river Arnon, and so entering it from the north, or by going round the southern point of the Dead Sea, and advancing through the northern portion of the mountains of Edom, and thus entering it from the south. The latter way was the longer of the two, and the one attended with the greatest difficulties and dangers, because the army would have to cross mountains which were very difficult to ascend. Nevertheless Jehoshaphat decided in its favour, partly because, if they took the northern route, they would have the Syrians at Ramoth in Gilead to fear, partly also because the Moabites, from their very confidence in the inaccessibility of their southern boundary, would hardly expect any attack from that side, and might therefore, if assailed at that point, be taken off their guard and easily defeated, and probably also from a regard to the king of Edom, whom they could induce to join them with his troops if they took that route, not so much perhaps for the purpose of strengthening their own army as to make sure of his forces, namely, that he would not make a fresh attempt at rebellion by a second invasion of the kingdom of Judah while Jehoshaphat was taking the field against the Moabites.