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.