20 But the prophet who presumes to speak a word in my name which I have not commanded him to speak, or who speaks in the name of other gods, that same prophet shall die.' 21 And if you say in your heart, 'How may we know the word which the Lord has not spoken?' -- 22 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 which the Lord has not spoken; the prophet has spoken it presumptuously, you need not be afraid of him.
Matthew Henry's Commentary on Deuteronomy 18:20-22
Commentary on Deuteronomy 18:15-22
(Read Deuteronomy 18:15-22)
It is here promised concerning Christ, that there should come a Prophet, great above all the prophets; by whom God would make known himself and his will to the children of men, more fully and clearly than he had ever done before. He is the Light of the world, John 12:48. Woe then to those who refuse to hearken to His voice, to accept His salvation, or yield obedience to His sway! But happy they who trust in Him, and obey Him. He will lead them in the paths of safety and peace, until He brings them to the land of perfect light, purity, and happiness. Here is a caution against false prophets. It highly concerns us to have a right touchstone wherewith to try the word we hear, that we may know what that word is which the Lord has not spoken. Whatever is against the plain sense of the written word, or which gives countenance or encouragement to sin, we may be sure is not that which the Lord has spoken.