Deuteronomy 18

20 But the prophet, who being corrupted with pride, shall speak in my name things that I did not command him to say, or in the name of strange gods,shall be slain.

21 And if in silent thought thou answer: How shall I know the word that the Lord hath not spoken?

22Thou shalt have this sign: Whatsoever that same prophet foretelleth in the name of the Lord, and it cometh not to pass:that thing the Lord hath not spoken, but the prophet hath forged it by the pride of his mind: and therefore thou shalt not fear him.