דברי הימים ב, פרק ל״ד, פסוק ה׳

The sweeping campaign to rid the land of idol worship reached beyond the living, extending even to the priests who had already passed away. The king took the remains of these deceased idolatrous priests and burned their bones directly upon the very altars where they had once practiced their rituals. This severe act was designed to deeply disgrace the foreign cults and provide a tangible, physical display of their inherent impurity [ביאור שטיינזלץ]. By defiling the altars in this manner, the king brought the thorough purification of Judah and Jerusalem to its final completion.