Deuteronomy 18:20-22

American Standard Version

²⁰ But the prophet, that shall speak a word presumptuously in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, that same prophet shall die. ²¹ And if thou say in thy heart, How shall we know the word which Jehovah hath not spoken? ²² when a prophet speaketh in the name of Jehovah, if the thing follow not, nor come to pass, that is the thing which Jehovah hath not spoken: the prophet hath spoken it presumptuously, thou shalt not be afraid of him.