In my
book-length critique of Sola Scriptura, Not
By Scripture Alone: A Latter-day Saint Refutation of Sola Scriptura I
discuss Rev 22:18-19 and texts from Deuteronomy, the Letter of Aristeas, and 1
Enoch, showing that John was warning against those who would corrupt the text
of the book of Revelation.
Another
relevant text is that of Ezra 6:11, part of Darius’ decree:
Also I have made a
decree, that whosoever shall alter this word, let timber be pulled down from
his house, and being set up, let him be hanged thereon; and let his house be
made a dunghill for this.
In other words, anyone who would alter the text of Darius' decree would be killed! This is similar to the curses on finds on Rev 22 and other like-texts from canonical and non-canonical works, though Rev 22 et al are focused on the written text while Darius' comments are about the command and changes thereto.
I also
refute the claim of some Protestants that Rev 22:18-19 teaches Sola Scriptura, as well as all the other
relevant texts (e.g., 2 Tim 3:16-17; Heb 1:1-2).