Charles Spurgeon Commentary Revelation 22:18-19

"I testify unto every man that heareth the words of the prophecy of this book, if any man shall add unto them, God shall add unto him the plagues which are written in this book: and if any man shall take away from the words of the book of this prophecy, God shall take away his part from the tree of life, and out of the holy city, which are written in this book." — Revelation 22:18-19 (ASV)

For I testify to every man that heard the word of the prophecy of this book, If any man shall add to these things, God shall add to him the plague that are written in this book: and if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book. (Revelation 22:18–19)

God's revelation is perfect; to add to it or to take from it would equally mar it, and the terrible threats given here concerning those who do either the one or the other should prevent so great a crime against high heaven. Yet, alas! many have dared and still dare to commit it.