Sanctify now yourselves - Compare the marginal reference. Hezekiah follows David’s example, knowing, probably, that the priests had in the preceding time of idolatry contracted many defilements.
The “filthiness,” or “uncleanness” 2 Chronicles 29:16, might consist, in part, of mere dust and dirt, in part, of idolatrous objects introduced by Ahaz before he finally shut up the temple 2 Kings 16:10-16.