John Gills Exposition of the Bible Commentary

Verse 22 (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 .

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.

- John Gills Exposition of the Bible Commentary