Deuteronomy 18:20–22

But the prophet who presumes to speak a word in my name that I have not commanded him to speak, or who speaks in the name of other gods, that same prophet shall die.’ And if you say in your heart, ‘How may we know the word that the Lord has not spoken?’— when a prophet speaks in the name of the Lord, if the word does not come to pass or come true, that is a word that the Lord has not spoken; the prophet has spoken it presumptuously. You need not be afraid of him.

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, is to be put to death.”

You may say to yourselves, “How can we know when a message has not been spoken by the Lord?” 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, so do not be alarmed.

But the prophet who presumes to speak a message in my name that I have not commanded him to speak, or who speaks in the name of other gods—that prophet must die.’ You may say to yourself, ‘How can we recognize a message the Lord has not spoken?’ When a prophet speaks in the Lord’s name, and the message does not come true or is not fulfilled, that is a message the Lord has not spoken. The prophet has spoken it presumptuously. Do not be afraid of him.

But any prophet who falsely claims to speak in my name or who speaks in the name of another god must die.’

“But you may wonder, ‘How will we know whether or not a prophecy is from the Lord?’ If the prophet speaks in the Lord’s name but his prediction does not happen or come true, you will know that the Lord did not give that message. That prophet has spoken without my authority and need not be feared.

However, the prophet that behaves presumptuously by speaking a word in my name that I have not commanded him to speak, and who speaks in the name of other gods, then that prophet shall die.’ And if you say to yourself, ‘How can we know the word that Yahweh has not spoken it?’ Whenever what the prophet spoke in the name of Yahweh, the thing does not take place and does not come about, that is the thing that Yahweh has not spoken it. Presumptuously the prophet spoke it; you shall not fear him.”

But the prophet, which shall presume to speak a word in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, even that prophet shall die. And if thou say in thine heart, How shall we know the word which the Lord hath not spoken? When a prophet speaketh in the name of the Lord, if the thing follow not, nor come to pass, that is the thing which the Lord hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not be afraid of him.