Deuteronomy 18:20-22 - WEB
20
But the prophet, who shall speak a word presumptuously in my name, which I have not commanded him to speak, or who shall speak in the name of other gods, that same prophet shall die.
21
If you say in your heart, How shall we know the word which Yahweh has not spoken?
22
when a prophet speaks in the name of Yahweh, if the thing doesn`t follow, nor happen, that is the thing which Yahweh has not spoken: the prophet has spoken it presumptuously, you shall not be afraid of him.
Full Chapter