1 Kings 20:36 - Joseph Benson’s Commentary on the Old and New Testaments

Because thou hast not obeyed the voice of the Lord, a lion shall slay thee If the punishment seem too severe for so small a fault, let it be considered, 1st, That disobedience to God's express command, especially when delivered by a person known by the party disobeying to be a prophet, was a great sin, and no less than capital, Deuteronomy 18:19. 2d, This fault was much worse in a prophet, who very well knew the authority of God's commands, and this way of publishing them. 3d, 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 off.