Deuteronomy 18:22

22 Whatsoever words that prophet shall speak in the name of the Lord, and they shall not come true, and not come to pass, this the thing which the Lord has not spoken; that prophet has spoken wickedly: ye shall not spare him.

Deuteronomy 18:22 Meaning and Commentary

Deuteronomy 18:22

When a prophet speaketh in the name of the Lord
Says he comes from God, is sent by him, and has a commission from him to say so:

if the thing follow not, nor come to pass;
as the prophecy of Hananiah, ( Jeremiah 28:3 ) that is the thing which the Lord hath not spoken; or otherwise it would have come to pass, unless when a condition is either expressed or implied, as the repentance or disobedience of a people; see ( Jeremiah 18:7-10 )

but the prophet hath spoken it presumptuously;
in a bold and daring manner, with great impiety and impudence, out of his own head and heart, being a mere device and imagination of his own, which, not having the fear of God, he delivered as coming from the Lord:

thou shall not be afraid of him;
not only to reprove him for his wickedness, but also to punish him for it; showing no regard to the high character he assumes, nor to the great pretensions he makes to sanctity, knowledge, and familiarity with God.

Deuteronomy 18:22 In-Context

20 But the prophet whosoever shall impiously speak in my name a word which I have not commanded him to speak, and whosoever shall speak in the name of other gods, that prophet shall die.
21 But if thou shalt say in thine heart, How shall we know the word which the Lord has not spoken?
22 Whatsoever words that prophet shall speak in the name of the Lord, and they shall not come true, and not come to pass, this the thing which the Lord has not spoken; that prophet has spoken wickedly: ye shall not spare him.

The Brenton translation of the Septuagint is in the public domain.