The rabbinical commentators conjecture that this prophet was Micaiah, the son of Imlah, who is mentioned below 1 Kings 22:8.

Hast thou seen all this great multitude? - The boast of Ben-hadad 1 Kings 20:10, was not without a basis of truth; his force seems to have exceeded 130, 000 (compare 1 Kings 20:25, 1 Kings 20:29-30). In his wars with the Assyrians we find him sometimes at the head of 100, 000 men.

There came a prophet - Who this was we cannot tell; Jarchi says it was Micaiah, son of Imlah. It is strange that on such an occasion we hear nothing of Elijah or Elisha. Is it not possible that this was one of them disguised?

And, behold, there came a prophet unto Ahab king of Israel,.... Supposed by the Jewish writers to be Micaiah the son of Imlah, 1 Kings 22:9 one of those perhaps that Obadiah hid in the cave, and now is sent out publicly on an errand to Ahab:

saying, thus saith the Lord, hast thou seen all this great multitude? considered what a vast number Benhadad's army consisted of:

behold, I will deliver it into thine hand this day; as great as it is:

and thou shalt know that I am the Lord; and not Baal, who can save by few as well as by many, and from a great multitude.

While the Syrians were preparing for the attack, a prophet came to Ahab and told him that Jehovah would deliver this great multitude (of the enemy) into his hand that day, "that thou mayest know that I am Jehovah," and that through the retainers of the governors of the provinces (המּדינות שׂרי, who had fled to Samaria), i.e., by a small and weak host. In the appearance of the prophet in Samaria mentioned here and in 1 Kings 20:28, 1 Kings 20:35. there is no such irreconcilable contradiction to 1 Kings 18:4, 1 Kings 18:22, and 1 Kings 19:10, as Thenius maintains; it simply shows that the persecution of the prophets by Jezebel had somewhat abated, and therefore Elijah's labour had not remained without fruit. מי יאסר הם, who shall open the battle? אסר answers to the German anfdeln (to string, unite; Eng. join battle - Tr.); cf. 2 Chronicles 13:3.

And, behold, there came a prophet unto Ahab king of Israel, saying, Thus saith the LORD, Hast thou seen all this great multitude? behold, I will deliver it into thine hand this day; and thou shalt know {g} that I am the LORD.

(g) Before God went about with signs and miracles to pull Ahab from his impiety, and now again with wonderful victories.

20:13 And behold, and c. - God, though forsaken and neglected by Ahab, prevents him with his gracious promise of help: that Ahab and the idolatrous Israelites, might hereby be fully convinced, or left without excuse, that Ben - hadad's intolerable pride, and contempt of God, and of his people, might be punished: and that the remnant of his prophets and people who were involved in the same calamity with the rest of the Israelites, might be preserved and delivered. I am the Lord - And not Baal, because I will deliver thee, which he cannot do.

came: Heb. approached

1Ki 20:13-20. The Syrians Are Slain.

13-21. behold, there came a prophet unto Ahab-Though the king and people of Israel had highly offended Him, God had not utterly cast them off. He still cherished designs of mercy towards them, and here, though unasked, gave them a signal proof of His interest in them, by a prophet's animating announcement that the Lord would that day deliver the mighty hosts of the enemy into his hand by means of a small, feeble, inadequate band. Conformably to the prophet's instructions, two hundred thirty-two young men went boldly out towards the camp of the enemy, while seven thousand more, apparently volunteers, followed at some little distance, or posted themselves at the gate, to be ready to reinforce those in front if occasion required it. Ben-hadad and his vassals and princes were already, at that early hour-scarcely midday-deep in their cups; and though informed of this advancing company, yet confiding in his numbers, or it may be, excited with wine, he ordered with indifference the proud intruders to be taken alive, whether they came with peaceful or hostile intentions. It was more easily said than done; the young men smote right and left, making terrible havoc among their intended captors; and their attack, together with the sight of the seven thousand, who soon rushed forward to mingle in the fray, created a panic in the Syrian army, who immediately took up flight. Ben-hadad himself escaped the pursuit of the victors on a fleet horse, surrounded by a squadron of horse guards. This glorious victory, won so easily, and with such a paltry force opposed to overwhelming numbers, was granted that Ahab and his people might know (1Ki 20:13) that God is the Lord. But we do not read of this acknowledgment being made, or of any sacrifices being offered in token of their national gratitude.

20:12-21 The proud Syrians were beaten, and the despised Israelites were conquerors. The orders of the proud, drunken king disordered his troops, and prevented them from attacking the Israelites. Those that are most secure, are commonly least courageous. Ahab slew the Syrians with a great slaughter. God often makes one wicked man a scourge to another.