And the prophets shall become wind, and the word is not in them: thus shall it be done unto them. And the prophets shall become wind - What are the prophets?
Empty persons. Their words are wind; we hear the sound of their threatening but of the matter of the threatenings we shall hear no more.
And the word is not in them - There is no inspirer, but may their own predictions fall on their own heads! This seems the natural sense of this passage.