Deuteronomy 18:20–22

20 But a prophet who presumes to speak in my name anything I have not commanded, or a prophet who speaks in the name of other gods,l is to be put to death.”m

21 You may say to yourselves, “How can we know when a message has not been spoken by the Lord?” 22 If what a prophet proclaims in the name of the Lord does not take place or come true,n that is a message the Lord has not spoken.o That prophet has spoken presumptuously,p so do not be alarmed.