Deuteronomy 18:21-22

New American Standard Bible

²¹ And if you say in your heart, ‘How will we recognize the word which the Lord has not spoken?’ ^22 (A)When the prophet speaks in the name of the Lord, and the thing does not happen or come true, that is the thing which the Lord has not spoken. The prophet has spoken it ^(B)presumptuously; you are not to be afraid of him.