John Wesley on 2 Kings 12:20

And slew Joash - We are told, in the Chronicles, that his murdering the prophet, Jehoiada's son, was the provocation. In this, how unrighteous so ever they were, yet the Lord was righteous. And this was not the only time, that he let even kings know, it was at their peril, if they touched his anointed, or did his prophets any harm. Thus fell Joash, who began in the spirit, and ended in the flesh. And indeed God usually sets marks of his displeasure upon apostates, even in this life.