Ezekiel 33:31-33

And they come unto thee as the people cometh, and they sit before thee as my people, and they hear thy words, but do them not; for with their mouth they show much love, but their heart goeth after their gain. And, lo, thou art unto them as a very lovely song of one that hath a pleasant voice, and can play well on an instrument; for they hear thy words, but they do them not. And when this cometh to pass (behold, it cometh), then shall they know that a prophet hath been among them.