6 For Pekah the son of Remaliah slew in Judah an hundred and twenty thousand in one day, which were all valiant valiant...: Heb. sons of valour men; because they had forsaken the Lord God of their fathers.
English Standard Version
6 For Pekah the son of Remaliah killed 120,000 from Judah in one day, all of them men of valor, because they had forsaken the Lord, the God of their fathers.
6 Pekah son of Remaliah killed 120,000 in one day, all of them first-class soldiers, and all because they had deserted God, the God of their ancestors.
New King James Version
6 For Pekah the son of Remaliah killed one hundred and twenty thousand in Judah in one day, all valiant men, because they had forsaken the Lord God of their fathers.
New Living Translation
6 In a single day Pekah son of Remaliah, Israel's king, killed 120,000 of Judah's troops, all of them experienced warriors, because they had abandoned the Lord, the God of their ancestors.
Matthew Henry's Commentary on 2 Chronicles 28:6
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.