Isaiah 6:11

How long - The prophet did not dare to pray that this effect should not follow. He asked merely therefore “how long” this state of things must continue; how long this message was to be delivered, and how long it should be attended with these painful effects.

Until the cities ... - They will remain perverse and obstinate until the land is completely destroyed by divine judgments. Still the truth is to be proclaimed, though it is known it will have no effect in reforming the nation. This refers, doubtless, to the destruction that was accomplished by the Babylonians.

The houses without man - This is strong language, denoting the certain and widespread desolation that should come upon the nation.