Deuteronomy 18:20-22

Geneva(i) 20 But the prophet that shall presume to speake a worde in my name, which I haue not commanded him to speake, or that speaketh in the name of other gods, euen the same prophet shall die. 21 And if thou thinke in thine heart, Howe shall we knowe the worde which the Lord hath not spoken? 22 When a prophet speaketh in the Name of the Lord, if the thing follow not nor come to passe, that is the thing which the Lord hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not therefore be afraid of him.