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) 20:1
kg2 20:1HEZEKIAH'S LIFE LENGTHENED. (Kg2 20:1-7)
In those days was Hezekiah sick--As his reign lasted twenty-nine years (Kg2 18:2), and his kingdom was invaded in the fourteenth (Kg2 18:13), it is evident that this sudden and severe illness must have occurred in the very year of the Syrian invasion. Between the threatened attack and the actual appearance of the enemy, this incident in Hezekiah's history must have taken place. But according to the usage of the sacred historian, the story of Sennacherib is completed before entering on what was personal to the king of Judah (see also Isa. 37:36-38:1).
Set thine house in order--Isaiah, being of the blood royal, might have access to the king's private house. But since the prophet was commissioned to make this announcement, the message must be considered as referring to matters of higher importance than the settlement of the king's domestic and private affairs. It must have related chiefly to the state of his kingdom, he having not as yet any son (compare Kg2 20:6 with Kg2 21:1).
for thou shall die, and not live--The disease was of a malignant character and would be mortal in its effects, unless the healing power of God should miraculously interpose.
4 Kings (2 Kings) 20:2
kg2 20:2he turned his face to the wall--not like Ahab (Kg1 21:4), in fretful discontent, but in order to secure a better opportunity for prayer.
4 Kings (2 Kings) 20:3
kg2 20:3remember now how I have walked before thee, &c.--The course of Hezekiah's thoughts was evidently directed to the promise made to David and his successors on the throne (Kg1 8:25). He had kept the conditions as faithfully as human infirmity admitted; and as he had been all along free from any of those great crimes by which, through the judgment of God, human life was often suddenly cut short, his great grief might arise partly from the love of life, partly from the obscurity of the Mosaic dispensation, where life and immortality had not been fully brought to light, and partly from his plans for the reformation of his kingdom being frustrated by his death. He pleaded the fulfilment of the promise.
4 Kings (2 Kings) 20:4
kg2 20:4afore Isaiah was gone out into the middle court--of the royal castle.
4 Kings (2 Kings) 20:5
kg2 20:5Thus saith . . . the God of David thy father--An immediate answer was given to his prayer, containing an assurance that the Lord was mindful of His promise to David and would accomplish it in Hezekiah's experience, both by the prolongation of his life, and his deliverance from the Assyrians.
on the third day--The perfect recovery from a dangerous sickness, within so short a time, shows the miraculous character of the cure (see his thanksgiving song, Isa 38:9). The disease cannot be ascertained; but the text gives no hint that the plague was raging then in Jerusalem; and although Arab physicians apply a cataplasm of figs to plague-boils, they also do so in other cases, as figs are considered useful in ripening and soothing inflammatory ulcers.
4 Kings (2 Kings) 20:8
kg2 20:8THE SUN GOES TEN DEGREES BACKWARD. (Kg2 20:8-20)
Hezekiah said unto Isaiah, What will be the sign that the Lord shall heal me--His recovery in the course of nature was so unlooked for, that the king asked for some token to justify his reliance on the truth of the prophet's communication; and the sign he specified was granted to him. The shadow of the sun went back upon the dial of Ahaz the ten degrees it had gone down. Various conjectures have been formed as to this dial. The word in the original is "degrees," or "steps," and hence many commentators have supposed that it was a stair, so artfully contrived, that the shadows on the steps indicated the hours and course of the sun. But it is more probable that it was a proper instrument, and, from the Hebrews having no term to designate it, that it was one of the foreign novelties imported from Babylon by Ahaz. It seems to have been of such magnitude, and so placed in the court, that Isaiah could point to it, and the king see it, from his chamber. The retrogression of the sun's shadow on the dial was miraculously accomplished by the omnipotent power of God; but the phenomenon was temporary, local, confined to the notice, and intended for the satisfaction, only of Hezekiah and his court.
4 Kings (2 Kings) 20:12
kg2 20:12Berodach-baladan-- (Isa 39:1), the first king of Babylon mentioned in sacred history; formerly its rulers were viceroys of the Assyrian monarchs. This individual threw off the yoke, and asserting his independence, made with varying success, a long and obstinate resistance [RAWLINSON, Outlines]. The message of congratulation to Hezekiah, was, in all likelihood, accompanied with proposals for a defensive alliance against their common Assyrian enemy. The king of Judah, flattered with this honor, showed the ambassadors all his treasures, his armory and warlike stores; and his motive for this was evidently that the Babylonian deputies might be the more induced to prize his friendship.
4 Kings (2 Kings) 20:13
kg2 20:13the silver, and the gold--He paid so much tribute to Sennacherib as exhausted his treasury (compare Kg2 18:16). But, after the destruction of Sennacherib, presents were brought him from various quarters, out of respect to a king who, by his faith and prayer, saved his country; and besides, it is by no means improbable that from the corpses in the Assyrian camp, all the gold and silver he had paid might be recovered. The vain display, however, was offensive to his divine liege lord, who sent Isaiah to reprove him. The answer he gave the prophet (Kg2 22:14) shows how he was elated by the compliment of their visit; but it was wrong, as presenting a bait for the cupidity of these rapacious foreigners, who, at no distant period, would return and pillage his country, and transfer all the possessions he ostentatiously displayed to Babylon, as well as his posterity to be court attendants in that country--(see on Ch2 32:31).
4 Kings (2 Kings) 20:19
kg2 20:19Good is the word of the Lord which thou hast spoken--indicating a humble and pious resignation to the divine will. The concluding part of his reply was uttered after a pause and was probably an ejaculation to himself, expressing his thankfulness, that, though great afflictions should befall his descendants, the execution of the divine judgment was to be suspended during his own lifetime.
4 Kings (2 Kings) 20:20
kg2 20:20pool and a conduit--(See on Ch2 32:30).