2 Kings 3:26-27

26When the king of Moab saw that the battle was too fierce for him, he took seven hundred swordsmen with him to try to break through to the king of Edom, but they could not do it.

27So he took his firstborn son, who was to become king in his place, and offered him as a burnt offering on the city wall. Great wrath was on the Israelites, and they withdrew from him and returned to their land.