Deuteronomy 18:21-22 New King James Version (NKJV)

21. And if you say in your heart, ‘How shall we know the word which the Lord has not spoken?’—

22. when a prophet speaks in the name of the Lord, if the thing does not happen or come to pass, that is the thing which the Lord has not spoken; the prophet has spoken it presumptuously; you shall not be afraid of him.

Deuteronomy 18