Charles Ellicott Commentary 1 Kings 20:13

"And, behold, a prophet came near unto Ahab king of Israel, and said, Thus saith Jehovah, Hast thou seen all this great multitude? behold, I will deliver it into thy hand this day; and thou shalt know that I am Jehovah." — 1 Kings 20:13 (ASV)

There came a prophet. —The appearance of this unknown prophet evidently shows (see also 1 Kings 22:6–7) that Ahab’s enmity toward the prophetic order had ended after the great day at Carmel, and that the schools of the prophets were forming again—perhaps not free from connection with the idolatry of Jeroboam, but safe from all attacks by the worshippers of Baal.

It is notable that Elijah does not appear in any of these political functions of prophecy, reserving himself for the higher moral and religious mission from God.

Ahab receives the prophet’s message with perfect confidence and reverence; he has, by outward profession, returned to his allegiance to Jehovah, an allegiance which he had, perhaps, never wholly relinquished.