Add thou not unto his words,.... To the words of God; as the Jews did, by joining their oral law, or the traditions of the elders, to the written word, and preferring them before it; and as the Papists, by making their unwritten traditions, and the sense and determinations of their church, equal to the Scriptures; and as all enthusiasts do, who set up their pretended dreams, visions, revelations, and prophecies, upon a foot with the word of God, or as superior to it; whereas that is, and that only, the rule and standard of faith and practice, and is a sufficient and perfect one; see Deu 4:2; lest he reprove thee; that is, God; either by words or by blows, by threatenings and denunciations of his wrath and displeasure; or by chastisements and corrections for such daring pride, blasphemy, and wickedness; those who add to his words, he threatens to add plagues unto them, Rev 22:18; and thou be found a liar; a forger, speaker, and spreader of doctrinal lies, such doctrines as are contrary to the word of truth; not being built on that, but upon human inventions, and additions to it.