Deut 18:20-22 (NIV) But a
prophet who presumes to speak in my name anything
I have not commanded him to say, or a prophet
who speaks in the name of other gods, must be put to
death."
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, that is a message the LORD has
not spoken. That prophet has spoken
presumptuously. Do not be afraid of him.