Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[37] When the prophet had said this, the next day, before the sun-rising, a great torrent ran strongly; for God had caused it to rain very plentifully at the distance of three days' journey into Edom, so that the army and the cattle found water to drink in abundance. But when the Moabites heard that the three kings were coming upon them, and made their approach through the wilderness, the king of Moab gathered his army together presently, and commanded them to pitch their camp upon the mountains, that when the enemies should attempt to enter their country, they might not be concealed from them. But when at the rising of the sun they saw the water in the torrent, for it was not far from the land of Moab, and that it was of the color of blood, for at such a time the water especially looks red, by the shining of the sun upon it, they formed a false notion of the state of their enemies, as if they had slain one another for thirst; and that the river ran with their blood. However, supposing that this was the case, they desired their king would send them out to spoil their enemies; whereupon they all went in haste, as to an advantage already gained, and came to the enemy's camp, as supposing them destroyed already. But their hope deceived them; for as their enemies stood round about them, some of them were cut to pieces, and others of them were dispersed, and fled to their own country. And when the kings fell into the land of Moab, they overthrew the cities that were in it, and spoiled their fields, and marred them, filling them with stones out of the brooks, and cut down the best of their trees, and stopped up their fountains of water, and overthrew their walls to their foundations. But the king of Moab, when he was pursued, endured a siege; and seeing his city in danger of being overthrown by force, made a sally, and went out with seven hundred men, in order to break through the enemy's camp with his horsemen, on that side where the watch seemed to be kept most negligently; and when, upon trial, he could not get away, for he lighted upon a place that was carefully watched, he returned into the city, and did a thing that showed despair and the utmost distress; for he took his eldest son, who was to reign after him, and lifting him up upon the wall, that he might be visible to all the enemies, he offered him as a whole burnt-offering to God, whom, when the kings saw, they commiserated the distress that was the occasion of it, and were so affected, in way of humanity and pity, that they raised the siege, and every one returned to his own house. So Jehoshaphat came to Jerusalem, and continued in peace there, and outlived this expedition but a little time, and then died, having lived in all sixty years, and of them reigned twenty-five. He was buried in a magnificent manner in Jerusalem, for he had imitated the actions of David.