Bible Warns Against Adding or Taking Away From Scriptures

"I warn everyone who hears the words of the prophecy of this book: If anyone adds anything to them, God will add to him the plagues described in this book. ¹⁹ And if anyone takes words away from this book of prophecy, God will take away from him his share in the tree of life and in the holy city, which are described in this book."  (Revelation 22:18-19)
--BibleGateway.com

http://www.biblegateway.com/passage/?search=Revelation%2022:18-19&version=NIV1984