Deuteronomy 18:19-21

American Standard Version

¹⁹ And it shall come to pass, that whosoever will not hearken unto my words which he shall speak in my name, I will require it of him.

²⁰ But the prophet, that shall speak a word presumptuously in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, that same prophet shall die. ²¹ And if thou say in thy heart, How shall we know the word which Jehovah hath not spoken?