Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

Isaiah replied with this comforting promise: Hezekiah was not to be afraid of the blasphemous words of the Assyrian king; the Lord would frighten him with a report, so that he would return to his own land, and there would He cause him to fall by the sword. מלך א נערי, the servants or young men of the Assyrian king, is a derogatory epithet applied to the officials of Assyria. "Behold, I put a spirit into him, so that he shall hear a report and return into his own land." שׁמוּעה does not refer to the report of the destruction of his army (Kg2 19:35), as Thenius supposes, for Sennacherib did not hear of this through the medium of an army, but was with the army himself at the time when it was smitten by the angel of the Lord; it refers to the report mentioned in Kg2 19:9. For even if he made one last attempt to secure the surrender of Jerusalem immediately upon hearing this report, yet after the failure of this attempt to shake the firmness of Hezekiah his courage must have failed him, and the thought of return must have suggested itself, so that this was only accelerated by the blow which fell upon the army. For, as O. v. Gerlach has correctly observed, "the destruction of the army would hardly have produced any decisive effect without the approach of Tirhakah, since the great power of the Assyrian king, especially in relation to the small kingdom of Judah, was not broken thereby. But at the prayer of the king the Lord added this miracle to the other, which His providence had already brought to pass. - For the fulfilment of the prophecy of Sennacherib's death, see Kg2 19:37.