A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
4 Kings (2 Kings) 19:1
kg2 19:1HEZEKIAH IN DEEP AFFLICTION. (Kg2 19:1-5)
when king Hezekiah heard it, he rent his clothes--The rending of his clothes was a mode of expressing horror at the daring blasphemy--the assumption of sackcloth a sign of his mental distress--his entrance into the temple to pray the refuge of a pious man in affliction--and the forwarding an account of the Assyrian's speech to Isaiah was to obtain the prophet's counsel and comfort. The expression in which the message was conveyed described, by a strong figure, the desperate condition of the kingdom, together with their own inability to help themselves; and it intimated also a hope, that the blasphemous defiance of Jehovah's power by the impious Assyrian might lead to some direct interposition for the vindication of His honor and supremacy to all heathen gods.
4 Kings (2 Kings) 19:4
kg2 19:4the living God--"The living God" is a most significant expression taken in connection with the senseless deities that Rab-shakeh boasted were unable to resist his master's victorious arms.
4 Kings (2 Kings) 19:6
kg2 19:6COMFORTED BY ISAIAH. (Kg2 19:6-7)
Isaiah said . . . Be not afraid--The prophet's answer was most cheering, as it held out the prospect of a speedy deliverance from the invader. The blast, the rumor, the fall by the sword, contained a brief prediction that was soon fulfilled in all the three particulars--namely, the alarm that hastened his retreat, the destruction that overtook his army, and the violent death that suddenly ended his career.
4 Kings (2 Kings) 19:8
kg2 19:8SENNACHERIB SENDS A BLASPHEMOUS LETTER TO HEZEKIAH. (Kg2 19:8-13)
So Rab-shakeh . . . found the king of Assyria warring against Libnah--Whether Lachish had fallen or not, is not said. But Sennacherib had transferred his battering-rams against the apparently neighboring fortress of Libnah (Jos 10:29; compare Jos 10:31; Jos 15:42), where the chief-cup-bearer reported the execution of his mission.
4 Kings (2 Kings) 19:9
kg2 19:9when he heard say of Tirhakah . . ., Behold, he is come out to fight against thee, &c.--This was the "rumor" to which Isaiah referred [Kg2 19:7]. Tirhakah reigned in Upper Egypt, while So (or Sabaco) ruled in Lower Egypt. He was a powerful monarch, another Sesostris, and both he and Sabaco have left many monuments of their greatness. The name and figure of Tirhakah receiving war captives, are still seen in the Egyptian temple of Medinet Abou. This was the expected succor which was sneered at by Rab-shakeh as "a bruised reed" (Kg2 18:21). Rage against Hezekiah for allying himself with Egypt, or the hope of being better able to meet this attack from the south, induced him, after hearing the rumor of Tirhakah's advance, to send a menacing letter to Hezekiah, in order that he might force the king of Judah to an immediate surrender of his capital. This letter, couched in the same vaunting and imperious style as the speech of Rab-shakeh, exceeded it in blasphemy, and contained a larger enumeration of conquered places, with the view of terrifying Hezekiah and showing him the utter hopelessness of all attempts at resistance.
4 Kings (2 Kings) 19:14
kg2 19:14HEZEKIAH'S PRAYER. (2Ki. 19:14-34)
Hezekiah received the letter . . . and went up into the house of the Lord--Hezekiah, after reading it, hastened into the temple, spread it in the childlike confidence of faith before the Lord, as containing taunts deeply affecting the divine honor, and implored deliverance from this proud defier of God and man. The devout spirit of this prayer, the recognition of the Divine Being in the plenitude of His majesty--so strikingly contrasted with the fancy of the Assyrians as to His merely local power; his acknowledgment of the conquests obtained over other lands; and of the destruction of their wooden idols which, according to the Assyrian practice, were committed to the flames--because their tutelary deities were no gods; and the object for which he supplicated the divine interposition--that all the kingdoms of the earth might know that the Lord was the only God--this was an attitude worthy to be assumed by a pious theocratic king of the chosen people.
4 Kings (2 Kings) 19:20
kg2 19:20Then Isaiah . . . sent--A revelation having been made to Isaiah, the prophet announced to the king that his prayer was heard. The prophetic message consisted of three different portions:--First, Sennacherib is apostrophized (Kg2 19:21-28) in a highly poetical strain, admirably descriptive of the turgid vanity, haughty pretensions, and presumptuous impiety of the Assyrian despot. Secondly, Hezekiah is addressed (Kg2 19:29-31), and a sign is given him of the promised deliverance--namely, that for two years the presence of the enemy would interrupt the peaceful pursuits of husbandry, but in the third year the people would be in circumstances to till their fields and vineyards and reap the fruits as formerly. Thirdly, the issue of Sennacherib's invasion is announced (Kg2 19:32-34).
4 Kings (2 Kings) 19:33
kg2 19:33shall not come into this city--nor approach near enough to shoot an arrow, not even from the most powerful engine which throws missiles to the greatest distance, nor shall he occupy any part of the ground before the city by a fence, a mantelet, or covering for men employed in a siege, nor cast (raise) a bank (mound) of earth, overtopping the city walls, whence he may see and command the interior of the city. None of these, which were the principal modes of attack followed in ancient military art, should Sennacherib be permitted to adopt. Though the army under Rab-shakeh marched towards Jerusalem and encamped at a little distance with a view to blockade it, they delayed laying siege to it, probably waiting till the king, having taken Lachish and Libnah, should bring up his detachment, that with all the combined forces of Assyria they might invest the capital. So determined was this invader to conquer Judah and the neighboring countries (Isa 10:7), that nothing but a divine interposition could have saved Jerusalem. It might be supposed that the powerful monarch who overran Palestine and carried away the tribes of Israel, would leave memorials of his deeds on sculptured slabs, or votive bulls. A long and minute account of this expedition is contained in the Annals of Sennacherib, a translation of which has recently been made into English, and, in his remarks upon it, COLONEL RAWLINSON says the Assyrian version confirms the most important features of the Scripture account. The Jewish and Assyrian narratives of the campaign are, indeed, on the whole, strikingly illustrative of each other [Outlines of Assyrian History].
4 Kings (2 Kings) 19:35
kg2 19:35AN ANGEL DESTROYS THE ASSYRIANS. (Kg2 19:35-36)
in the morning . . . they were all dead corpses--It was the miraculous interposition of the Almighty that defended Jerusalem. As to the secondary agent employed in the destruction of the Assyrian army, it is most probable that it was effected by a hot south wind, the simoon, such as to this day often envelops and destroys whole caravans. This conjecture is supported by Kg2 19:7 and Jer 51:1. The destruction was during the night; the officers and soldiers, being in full security, were negligent; their discipline was relaxed; the camp guards were not alert, or perhaps they themselves were the first taken off, and those who slept, not wrapped up, imbibed the poison plentifully. If this had been an evening of dissolute mirth (no uncommon thing in a camp), their joy (perhaps for a victory), or "the first night of their attacking the city," says JOSEPHUS, became, by its effects, one means of their destruction [CALMET, Fragments].
4 Kings (2 Kings) 19:36
kg2 19:36So Sennacherib king of Assyria . . . went and returned--the same way as he came (Kg2 19:33). The route is described (Isa 10:28-32). The early chariot track near Beyrout is on the rocky edge of Lebanon, which is skirted by the ancient Lycus (Nahr-el Kelb). On the perpendicular face of the limestone rock, at different heights, are seen slabs with Assyrian inscriptions, which having been deciphered, are found to contain the name of Sennacherib. Thus, by the preservation of these tablets, the wrath of the Assyrian invaders is made to praise the Lord.
dwelt at Nineveh--This statement implies a considerable period of time, and his Annals carry on his history at least five years after his disastrous campaign at Jerusalem. No record of his catastrophe can be found, as the Assyrian practice was to record victories alone. The sculptures give only the sunny side of the picture.
4 Kings (2 Kings) 19:37
kg2 19:37SENNACHERIB SLAIN. (Kg2 19:37)
as he was worshipping in the house of Nisroch--Assarae, or Asshur, the head of the Assyrian Pantheon, represented not as a vulture-headed figure (that is now ascertained to be a priest), but as a winged figure in a circle, which was the guardian deity of Assyria. The king is represented on the monuments standing or kneeling beneath this figure, his hand raised in sign of prayer or adoration.
his sons smote him with the sword--Sennacherib's temper, exasperated probably by his reverses, displayed itself in the most savage cruelty and intolerable tyranny over his subjects and slaves, till at length he was assassinated by his two sons, whom, it is said, he intended to sacrifice to pacify the gods and dispose them to grant him a return of prosperity. The parricides taking flight into Armenia, a third son, Esar-haddon, ascended the throne.