'Vain words' in the Bible

Thou sayest (but they are but vain words), There is counsel and strength for the war. Now on whom dost thou trust, that thou hast rebelled against me?

Shall vain words have an end? Or what provoketh thee that thou answerest?

I say, thy counsel and strength for the war are but vain words: now on whom dost thou trust, that thou hast rebelled against me?

They speak vain words, swearing falsely in making covenants: therefore judgment springeth up as hemlock in the furrows of the field.