Truly, I believe the cut in Deuteronomy 4:2 is between the words of God versus the words of men:
I agree with you on adding or taking away from the Bible. Tradition does not do that. The Bible is still intact for Catholics. It’s just that other happenings were not recorded in the Gospels.
I can’t remember the direct quote from my priest, but he quoted something from St. Paul that is not in any Gospel and gives Jesus the credit for saying it. I’ll have to find out exactly what it is.
John, chapter 21
24It is this disciple who testifies to these things and has written them,* and we know that his testimony is true.n
25There are also many other things that Jesus did, but if these were to be described individually, I do not think the whole world would contain the books that would be written.
2 John, chapter 1
12* Although I have much to write to you, I do not intend to use paper and ink. Instead, I hope to visit you and to speak face to face so that our joy may be complete.h
13The children of your chosen sister* send you greetings.
13I have much to write to you, but I do not wish to write with pen and ink.h
14Instead, I hope to see you soon, when we can talk face to face. 15Peace be with you. The friends greet you; greet the friends* there each by name.i