Great thread!
Deut 18:20-22 : If any prophet presumptuously speaks a word in my name that I did not command him to speak or speaks in the name of other gods, that prophet must die. 21 However, you may say in your heart: “How will we know that Jehovah has not spoken the word?” 22 When the prophet speaks in the name of Jehovah and the word is not fulfilled or does not come true, then Jehovah did not speak that word. The prophet spoke it presumptuously. You should not fear him.’