Hebrews 9:23

It was necessary therefore that the copies of the things in the heavens should be cleansed with these; but the heavenly things with better sacrifices than these.

This verse concludes an argument the author began back in Hebrews 9:13, to the effect that Christ's sacrifice is infinitely more wonderful and efficacious than any or all of the Mosaic sacrifices. Bruce's illuminating comment on this is:

Our author does not deny that such ritual cleansing was real and effective as far as it went. What he does deny is that cleansing of this kind could be of any use for the removal of inward and spiritual defilement. The various installations that were cleansed and fitted for the worship of God by the blood of animal sacrifices were but copies of the spiritual realities; where the spiritual realities themselves are concerned, a superior sacrifice and more effective cleansing must be forthcoming. It has frequently been asked in what sense the "heavenly things" required to be cleansed; but our author has provided the answer in the context. What required to be cleansed was the defiled consciences of men and women; this is a cleansing which belongs to the spiritual sphere.[16]