How about these verses:
Rev. 22:18-19
Proverbs 30:5-6
Matthew: 24:24
Deut. 13:1-10
Those are a few I know but my brain is on vacation after my move
For example, you cite Rev 22:18-19. But Deuteronomy 4:2 said the same thing, "You shall not add to the word that I command you, nor take from it, that you may keep the commandments of the Lord your God that I command you.
Why is anything after Deu 4:2 relevant? It is all added.
Answer the questions asked with specifics, not just cut and paste.