No doubt the Lord overruled the minds of the Moabites to this delusion, in supposing what they beheld of the water to be blood. And indeed as they knew no rain had fallen, such an idea was not, altogether improbable. The victory of Israel, which Elisha had promised in the Lord's name, certainly was well followed up. It is remarkable upon this occasion, that the Israelites were permitted to act different from a known law! Deuteronomy 20:19.
2 Kings 3:21-25
21 And when all the Moabites heard that the kings were come up to fight against them, they gatheredc all that were able to put on armour, and upward, and stood in the border.
22 And they rose up early in the morning, and the sun shone upon the water, and the Moabites saw the water on the other side as red as blood:
23 And they said, This is blood: the kings are surely slain,d and they have smitten one another: now therefore, Moab, to the spoil.
24 And when they came to the camp of Israel, the Israelites rose up and smote the Moabites, so that they fled before them: but they went forward smiting the Moabites, even in their country.
25 And they beat down the cities, and on every good piece of land cast every man his stone, and filled it; and they stopped all the wells of water, and felled all the good trees: only in Kirharaseth left they the stones thereof; howbeit the slingers went about it, and smote it.