Revelation 22:18
I testify to everyone who hears the words of prophecy in this book: If anyone adds to them, God will add to him the plagues described in this book.
What it says
A warning is given that anyone adding to the prophecy will receive the plagues written in it.
What it is doing
This verse protects the integrity of the revealed message.
In context
18I testify to everyone who hears the words of prophecy in this book: If anyone adds to them, God will add to him the plagues described in this book. 19And if anyone takes away from the words of this book of prophecy, God will take away his share in the tree of life and the holy city, which are described in this book. 20He who testifies to these things says, “Yes, I am coming soon.” Amen. Come, Lord Jesus! 21The grace of the Lord Jesus be with all the saints.