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.
When a prophet speaks in Yahweh’s name, if the thing doesn’t follow, nor happen, that is the thing which Yahweh has not spoken. The prophet has spoken it presumptuously. You shall not be afraid of him.