Ahaz was twenty years old when he began to reign, and he reigned sixteen years in Jerusalem: but he did not that which was right in the sight of the LORD, like David his father:

Achaz was twenty years old when he began to reign, and he reigned sixteen years in Jerusalem: he did not that which was right in the sight of the Lord as David his father had done,

A son of twenty years is Ahaz in his reigning, and sixteen years he hath reigned in Jerusalem, and he hath not done that which is right in the eyes of Jehovah, as David his father,

Ahaz was twenty years old when he became king, and he was ruling in Jerusalem for sixteen years; he did not do what was right in the eyes of the Lord, like David his father:

Ahaz was twenty years old when he had begun to reign, and he reigned for sixteen years in Jerusalem. He did not do what is right in the sight of the Lord, as his father David did.

This chapter is supplemental in character, The writer seems to assume that the narrative of Kings (marginal reference) is known, and is mainly anxious to add points which the author of that narrative has omitted.

Ahaz was twenty years old - For the difficulties in this chronology, see the notes on 2-Kings 16:2 (note).

Ahaz was twenty years old when he began to reign,.... These verses are much the same with 2-Kings 16:2, only in 2-Chronicles 28:2 it is said,
he made also molten images for Baalim; the several Baals or idols of the nations round about, as well as served Jeroboam's calves; see Judges 2:11, and he is said in 2-Chronicles 28:3,
to burn incense in the valley of the son of Hinnom; to Molech, the god of the Ammonites, who was worshipped there. See Gill on 2-Kings 16:2, 2-Kings 16:3, 2-Kings 16:4.

Israel gained this victory because God was wroth with Judah, and made them the rod of his indignation. He reminds them of their own sins. It ill becomes sinners to be cruel. Could they hope for the mercy of God, if they neither showed mercy nor justice to their brethren? Let it be remembered, that every man is our neighbour, our brother, our fellow man, if not our fellow Christian. And no man who is acquainted with the word of God, need fear to maintain that slavery is against the law of love and the gospel of grace. Who can hold his brother in bondage, without breaking the rule of doing to others as he would they should do unto him? But when sinners are left to their own heart's lusts, they grow more desperate in wickedness. God commands them to release the prisoners, and they obeyed. The Lord brought Judah low. Those who will not humble themselves under the word of God, will justly be humbled by his judgments. It is often found, that wicked men themselves have no real affection for those that revolt to them, nor do they care to do them a kindness. This is that king Ahaz! that wretched man! Those are wicked and vile indeed, that are made worse by their afflictions, instead of being made better by them; who, in their distress, trespass yet more, and have their hearts more fully set in them to do evil. But no marvel that men's affections and devotions are misplaced, when they mistake the author of their trouble and of their help. The progress of wickedness and misery is often rapid; and it is awful to reflect upon a sinner's being driven away in his wickedness into the eternal world.

AHAZ, REIGNING WICKEDLY, IS AFFLICTED BY THE SYRIANS. (2Ch. 28:1-21)
Ahaz was twenty years old--(See on 2-Kings 16:1-4). This prince, discarding the principles and example of his excellent father, early betrayed a strong bias to idolatry. He ruled with an arbitrary and absolute authority, and not as a theocratic sovereign: he not only forsook the temple of God, but embraced first the symbolic worship established in the sister kingdom, and afterwards the gross idolatry practised by the Canaanites.

In the general statements as to the king's age, and the duration and the spirit of his reign, both accounts (2-Chronicles 28:1-4; 2-Kings 16:1-4), agree entirely, with the exception of some unessential divergences; see the commentary on 2-Kings 16:1-4. From 2-Chronicles 28:5 onwards both historians go their own ways, so that they coincide only in mentioning the most important events of the reign of this quite untheocratic king. The author of the book of Kings, in accordance with his plan, records only very briefly the advance of the allied kings Rezin and Pekah against Jerusalem, the capture of the seaport Elath by the Syrians, the recourse which the hard-pressed Ahaz had to the help of Tiglath-pileser the king of Assyria, whom he induced, by sending him the temple and palace treasures of gold and silver, to advance upon Damascus, to capture that city, to destroy the Syrian kingdom, to lead the inhabitants away captive to Kir, and to slay King Rezin (2-Chronicles 28:5-9). Then he records how Ahaz, on a visit which he paid the Assyrian king in Damascus, saw an altar which so delighted him, that he sent a pattern of it to the priest Urijah, with the command to build a similar altar for the temple of the Lord, on which Ahaz on his return not only sacrificed himself, but also commanded that all the sacrifices of the congregation should be offered. And finally, he recounts how he laid violent hands on the brazen vessels of the court, and caused the outer covered sabbath way to be removed into the temple because of the king of Assyria (2-Chronicles 28:10-18); and then the history of Ahaz is concluded by the standing formulae (2-Chronicles 28:19, 2-Chronicles 28:20). The author of the Chronicle, on the contrary, depicts in holy indignation against the crimes of the godless Ahaz, how God punished him for his sins. 1. He tells us how God gave Ahaz into the hand of the king of Syria, who smote him and led away many prisoners to Damascus, and into the hand of King Pekah of Israel, who inflicted on him a dreadful defeat, slew 120,000 men, together with a royal prince and two of the highest officials of the court, and carried away 200,000 prisoners-women and children-with a great booty (2-Chronicles 28:5-8); and how the Israelites yet, at the exhortation of the prophet Oded, and of some of the heads of the people who supported the prophet, again freed the prisoners, provided them with food and clothing, and conducted them back to Jericho (2-Chronicles 28:9-15). 2. He records that Ahaz turned to the king of Assyria for help (2-Chronicles 28:16), but that God still further humbled Israel by an invasion of the land by the Edomites, who carried prisoners away (2-Chronicles 28:17); by an attack of the Philistines, who deprived Judah of a great number of cities (2-Chronicles 28:18); and finally also by the Assyrian king Tiglath-pileser, who, although Ahaz had sent him the gold and silver of the temple and of the palaces of the kings and princes, yet did not help him, but rather oppressed him (2-Chronicles 28:20.). 3. Then he recounts how, notwithstanding all this, Ahaz sinned still more against Jahve by sacrificing to the idols of the Syrians, cutting up the vessels of the house of God, closing the doors of the temple, and erecting altars and high places in all corners of Jerusalem, and in all the cities of Judah, for the purpose of sacrificing to idols (2-Chronicles 28:22-25). This whole description is planned and wrought out rhetorically; cf. C. P. Caspari, der syrisch-ephraimitische Krieg, S. 42ff. Out of the historical materials, those facts which show how Ahaz, notwithstanding the heavy blows which Jahve inflicted upon him, always sinned more deeply against the Lord his God, are chosen, and oratorically so presented as not only to bring before us the increasing obduracy of Ahaz, but also, by the representation of the conduct of the citizens and warriors of the kingdom of Israel towards the people of Judah who were prisoners, the deep fall of that kingdom.