John Gill Commentary 2 Chronicles 34:5

"And he burnt the bones of the priests upon their altars, and purged Judah and Jerusalem." — 2 Chronicles 34:5 (ASV)

And he burnt the bones of the priests upon their altars
On which they sacrificed, in detestation of their idolatry, and to deter from it; and this he did according to the prophecy of him, above three hundred and fifty years before:

and cleansed Judah and Jerusalem ;
from idolatry, and all the monuments of it.