Scripture

19 Now the rest of the acts of Joash, and all that he did, are they not written in the Book of the Annals of the Kings of Judah? 20His servants arose, devised a conspiracy, and killed Joash in the house of Millo, on the way that goes down to Silla. 21It was Jozacar son of Shimeath and Jehozabad son of Shomer, his servants, who struck him down, so

If, after all, he looked like leading a whole town astray, then Deuteronomy 13:12–18 would come into play; it has been suggested that this was why several towns refused to countenance his teaching, since to do so would court disaster for them as well as for him.