Deuteronomy 17:12

17:12 The person who pays no attention to the priest currently serving the Lord your God there, or to the verdict – that person must die, so that you may purge evil from Israel.

Deuteronomy 18:22

18:22 whenever a prophet speaks in my name and the prediction is not fulfilled, then I have not spoken it; the prophet has presumed to speak it, so you need not fear him.”