Deuteronomy Chapter 18, Verse 22

22: When a prophet speaketh in the name of the LORD, if the thing follow not, nor come to pass, that is the thing which the LORD hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not be afraid of him.- edit KJV text
22: Thou 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.— edit Douay text
22: Whatsoever words that prophet shall speak in the name of the Lord, and they shall not come true, and not come to pass, this [is] the thing which the Lord has not spoken; that prophet has spoken wickedly: ye shall not spare him.— edit LXX text