3 Moreover he burnt incense in the valley of the son of Hinnom, and burnt burnt...: or, offered sacrifice his children in the fire, after the abominations of the heathen whom the Lord had cast out before the children of Israel.
English Standard Version
3 and he made offerings in the Valley of the Son of Hinnom and burned his sons as an offering,Hebrew made his sons pass through the fire according to the abominations of the nations whom the Lord drove out before the people of Israel.
3 He participated in the outlawed burning of incense in the Valley of Ben Hinnom and - incredibly! - indulged in the outrageous practice of "passing his sons through the fire," a truly abominable thing he picked up from the pagans God had earlier thrown out of the country.
New King James Version
3 He burned incense in the Valley of the Son of Hinnom, and burned his children in the fire, according to the abominations of the nations whom the Lord had cast out before the children of Israel.
New Living Translation
3 He offered sacrifices in the valley of Ben-Hinnom, even sacrificing his own sons in the fire. In this way, he followed the detestable practices of the pagan nations the Lord had driven from the land ahead of the Israelites.
Matthew Henry's Commentary on 2 Chronicles 28:3
The wicked reign of Ahaz in Judah.
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.