“For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:”
King James Version (KJV)
22:18-19 I testify to every one, &c. - From the fulness of his heart, the apostle utters this testimony, this weighty admonition, not only to the churches of Asia, but to all who should ever hear this book. He that adds, all the plagues shall be added to him; he that takes from it, all the blessings shall be taken from him; and, doubtless, this guilt is incurred by all those who lay hinderances in the way of the faithful, which prevent them from hearing their Lord's I come, and answering, Come, Lord Jesus. This may likewise be considered as an awful sanction, given to the whole New Testament; in like manner as Moses guarded the law, #Deut 4:2|, and Deut 12:32; and as God himself did, #Mal 4:4|, in closing the canon of the Old Testament.
Re 22:18 If any man shall add unto these things, God shall add unto him the plagues that are written in this book. See De 4:2 12:32. The whole spirit of the Scripture is against adding to or taking from the Lord's words. This is a warning against spurious revelations.