God should have been pleased with the second smiting, though, since it was "a great slaughter."
He [Ahaz] was also delivered into the hand of the king of Israel, who smote him with a great slaughter. 2 Chronicles 28.5bAnd it was a great slaughter, too. 120,000 valiant men died in one day! (And 200,000 women and children were taken for slaves.)
For Pekah the son of Remaliah slew in Judah an hundred and twenty thousand in one day, which were all valiant men; because they had forsaken the LORD God of their fathers. ... And the children of Israel carried away captive of their brethren two hundred thousand, women, sons, and daughters. 28.6-8But God wasn't pleased with this slaughter either. In fact, the fierce wrath of God was now on the smiters.
A prophet of the LORD was there, whose name was Oded: and he ... said unto them, Behold, because the LORD God of your fathers was wroth with Judah, he hath delivered them into your hand, and ye have slain them in a rage that reacheth up unto heaven. ... for the fierce wrath of the LORD is upon you. 28.9-11You see, in the first smiting, the Syrians didn't kill enough people; in the second, the Israelites killed too many. God has a golden mean, sort of a Goldilocks standard for smiting. I'm guessing that God thought that 60,000 to 80,000 was the proper amount of smiting to pay forward king Ahaz for his children/incense burning activities.
In any case, the Israelites worked things out with God by sending the slaves back to Judah and giving them their stuff back. And God forgot his rage toward the Israelites and moved on to his next killing.
God's next killing: Jerusalem