2 Kings 3:22,23

The sun shone upon the water, &c. They stood in such a situation, when they looked at the water, that those rays of the sun which gave a red colour, were reflected from the water to their eyes; or the light of the morning sun shining upon the water, through the vapours that arose from the earth, gave it a reddish appearance; so that they imagined it to be blood, which they were the more inclined to suppose, because they knew very well there was no water there before. And they said The kings are surely slain, &c. As they concluded what they saw could be nothing but blood, so they could not conceive it could be any other blood than that of the army of the three kings, who they thought had fallen out among themselves, vexed at the straits into which they had brought one another. Now therefore, Moab, to the spoil Easily believing what they wished, they imagined they had nothing to do but to go and take the spoil, having no need to fight at all. Therefore they sent no scouts, but marched thither with their whole army, and that in great disorder: wherein, also, there was a divine hand, strengthening them in their mistakes, and hardening them to their destruction.