The king of Edom, i.e. the viceroy under Jehoshaphat, 1 Kings 22:47, here called king; either because he was so called and accounted by his own people, or because that word is sometimes used for any prince or chief ruler. See Deuteronomy 33:5 Judges 18:1, Judges 21:25 1 Kings 20:1. They fetched a compass, because they made a great army, which could move but slowly; and they fetched a greater compass than was usual, for some advantage which they expected by it. There was no water; a frequent want in those hot and desert parts; and now, as it seems, increased by the extraordinary heat and dryness of the season.
Related Commentaries of 2 Kings 3:9
2 Kings 3:9
9 So the king of Israel went, and the king of Judah, and the king of Edom: and they fetched a compass of seven days' journey: and there was no water for the host, and for the cattle that followed them.