Deuteronomy 4:2

4:2 Do not add a thing to what I command you nor subtract from it, so that you may keep the commandments of the Lord your God that I am delivering to you.

Deuteronomy 12:32

Idolatry and False Prophets

12:32 (13:1) You must be careful to do everything I am commanding you. Do not add to it or subtract from it!

Revelation 22:18-19

22:18 I testify to the one who hears the words of the prophecy contained in this book: If anyone adds to them, God will add to him the plagues described in this book. 22:19 And if anyone takes away from the words of this book of prophecy, God will take away his share in the tree of life and in the holy city that are described in this book.