2Pe 1:20 Knowing this first, that no prophecy of the scripture is of any private interpretation.<quoted text>
First of all you must understand this, that no prophesy of Scripture is a matter of one's own interpretation, because no prophecy ever came by the impulse of man, but men moved by the Holy Spirit spoke from God.[2 Peter 1:20-21]"
You're off on a tangent.
The passage doesn't speak of prophesy AND/OR scripture-it's stated "prophesy OF Scripture", so it's already Scripture.
prophecy: profhteia propheteia:("prophecy "); prediction (scriptural or other):--prophecy, prophesying.
Its called Strong's Greek Lexicon.....
See: scriptural or other