1 Kings 20:42

And he said unto him, Thus saith the Lord, Because thou hast let go out of thy hand a man. whom I appointed to utter destruction, therefore thy life shall go for his life and thy people for his people; Ahab would be held responsible, he would have to pay the penalty. By letting the archenemy escape, he had practically denied the might, the goodness, and the justice of Jehovah, and both he and Israel would pay.