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) 16:1
kg2 16:1AHAZ' WICKED REIGN OVER JUDAH. (2Ki. 16:1-16)
Ahaz . . . did not that which was right in the sight of the Lord--[See on Ch2 28:1.] The character of this king's reign, the voluptuousness and religious degeneracy of all classes of the people, are graphically portrayed in the writings of Isaiah, who prophesied at that period. The great increase of worldly wealth and luxury in the reigns of Azariah and Jotham had introduced a host of corruptions, which, during his reign, and by the influence of Ahaz, bore fruit in the idolatrous practices of every kind which prevailed in all parts of the kingdom (see Ch2 28:24).
4 Kings (2 Kings) 16:3
kg2 16:3walked in the way of the kings of Israel--This is descriptive of the early part of his reign, when, like the kings of Israel, he patronized the symbolic worship of God by images but he gradually went farther into gross idolatry (Ch2 28:2).
made his son to pass through the fire-- (Kg2 23:10). The hands of the idol Moloch being red hot, the children were passed through between them, which was considered a form of lustration. There is reason to believe that, in certain circumstances, the children were burnt to death (Psa 106:37). This was strongly prohibited in the law (Lev 18:21; Lev 20:2-5; Deu 18:10), although there is no evidence that it was practised in Israel till the time of Ahaz.
4 Kings (2 Kings) 16:5
kg2 16:5Then Rezin king of Syria and Pekah son of Remaliah king of Israel came up to Jerusalem--Notwithstanding their great efforts and military preparations, they failed to take it and, being disappointed, raised the siege and returned home (compare Isa 7:1).
4 Kings (2 Kings) 16:6
kg2 16:6Rezin . . . recovered Elath--which Azariah had got into his possession (Kg2 14:22).
the Syrians came to Elath, and dwelt there unto this day--The Septuagint version has "the Edomites," which the most judicious commentators and travellers [ROBINSON] prefer.
4 Kings (2 Kings) 16:7
kg2 16:7So Ahaz sent messengers to Tiglath-pileser--In spite of the assurance given him by Isaiah by two signs, the one immediate, the other remote (Isa 7:14; Isa 8:4), that the confederate kings would not prevail against him, Ahaz sought aid from the Assyrian monarch, to purchase which he sent the treasures of the palace and temple. Tiglath-pileser marched against Damascus, slew Rezin the king, and carried the people of Damascus into captivity to Kir, which is thought to have been the city Karine (now Kerend), in Media.
4 Kings (2 Kings) 16:10
kg2 16:10And king Ahaz went to Damascus to meet Tiglath-pileser--This was a visit of respect, and perhaps of gratitude. During his stay in that heathen city, Ahaz saw an altar with which he was greatly captivated. Forthwith a sketch of it was transmitted to Jerusalem, with orders to Urijah the priest to get one constructed according to the Damascus model, and let this new altar supersede the old one in the temple. Urijah, with culpable complaisance, acted according to his instructions (Kg2 16:16). The sin in this affair consisted in meddling with, and improving according to human taste and fancy, the altars of the temple, the patterns of which had been furnished by divine authority (Exo 25:40; Exo 26:30; Exo 27:1; Ch1 28:19). Urijah was one of the witnesses taken by Isaiah to bear his prediction against Syria and Israel (Isa 8:2).
4 Kings (2 Kings) 16:17
kg2 16:17HE SPOILS THE TEMPLE. (Kg2 16:17-19)
cut off the borders of the bases, &c.--It is thought that he did this to use the elaborate sculpture in adorning his palace.
4 Kings (2 Kings) 16:18
kg2 16:18the covert for the Sabbath--the portico through which the priests entered the temple on the Sabbath.
the king's entry without--a private external entrance for the king into the temple. The change made by Ahaz consisted in removing both of these into the temple from fear of the king of Assyria, that, in case of a siege, he might secure the entrance of the temple from him.