1 Kings 20:36

Slew him — We cannot judge of the case; this man might be guilty of many other heinous sins unknown to us but known to God; for which, God might justly cut him off: which God chose to do upon this occasion, that by the severity of this punishment of a prophet's disobedience, proceeding from pity to his brother, he might teach Ahab the greatness of his sin, in sparing him through foolish pity, whom by the laws of religion, and justice, and prudence, he should have cut of.