Then Josiah looked around and saw some tombs there on the hill; he had the bones taken out of them and burned on the altar. In this way he desecrated the altar, doing what the prophet had predicted long before during the festival as King Jeroboam was standing by the altar. King Josiah looked around and saw the tomb of the prophet who had made this prediction. 1
References for 2 Kings 23:16
23.16 1 K 13.2.
"Whose tomb is that?" he asked. 2 The people of Bethel answered, "It is the tomb of the prophet who came from Judah and predicted these things that you have done to this altar."
References for 2 Kings 23:17
23.17 1 K 13.30-32.
"Leave it as it is," Josiah ordered. "His bones are not to be moved." So his bones were not moved, neither were those of the prophet who had come from Samaria.