Deuteronomy 18:20-22

Revised Standard Version Catholic Edition

²⁰ But the prophet who presumes to speak a word in my name which I have not commanded him to speak, or who speaks in the name of other gods, that same prophet shall die.’ ²¹ And if you say in your heart, ‘How may we know the word which the Lord has not spoken?’— ²² when a prophet speaks in the name of the Lord, if the word does not come to pass or come true, that is a word which the Lord has not spoken; the prophet has spoken it presumptuously, you need not be afraid of him.