Deuteronomy 4:2; Deuteronomy 12:32; Proverbs 30:6; Revelation 22:18

2 You shall not add to the word which I command you, nor take from it, that you may keep the commandments of the Lord your God which I command you.
32 Whatever I command you, be careful to observe it; you shall not add to it nor take away from it.
6 Do not add to His words, Lest He rebuke you, and you be found a liar.
18 For I testify to everyone who hears the words of the prophecy of this book: If anyone adds to these things, God will add to him the plagues that are written in this book;