Charles Ellicott Commentary 2 Kings 23:20

"And he slew all the priests of the high places that were there, upon the altars, and burned men`s bones upon them; and he returned to Jerusalem." — 2 Kings 23:20 (ASV)

He slew. — He slaughtered. This was a contrast to his mild treatment of the priests of the Judean high places (2 Kings 23:8–9). They were Levites, and these were heathenish priests . Thus was fulfilled the prophecy of 1 Kings 13:2. (Thenius considers the event historical, because that prophecy “is undoubtedly modelled upon it.”)