Charles Ellicott Commentary Isaiah 65:5

"that say, Stand by thyself, come not near to me, for I am holier than thou. These are a smoke in my nose, a fire that burneth all the day." — Isaiah 65:5 (ASV)

Which say, Stand by thyself ... —The picture, in its main outlines, reminds us of the proud exclusiveness of the later Pharisees, and the root-evil is, of course, identical. Here, however, the ground of the exclusiveness is not the consciousness of the peculiar privileges of Israel, but rests on what was an actual apostasy. Those of whom Isaiah speaks boasted of their initiation into heathen mysteries (Baal, Tammuz, or the like) as giving them a kind of consecrated character, and separating them from the profanum vulgus of the Israelites, who were faithful to the God of their fathers.

I am holier than thou. —Literally, I am holy to you: i.e., one whom you may not approach . By some commentators the verb is taken as transitive, I make you holy: i.e., have power to impart holiness; but this is less satisfactory, both grammatically and as to meaning.

These are a smoke in my nose ... —The point of the clause is that the punishment is represented as not future. The self-exalting idolaters are already as those who are being consumed in the fire of the Divine wrath, and their smoke is a savour of death in the nostrils of Jehovah.