“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.”
King James Version (KJV)
18:22 If the thing - Which he gives as a sign of the truth of his prophecy. The falsehood of his prediction shews him to be a false prophet. Presumptuously - Impudently ascribing his own vain and lying fancies to the God of truth.