Sola scriptura (Latin: by Scripture alone) is a Christian theological doctrine which holds that the Christian Scriptures are the sole infallible rule of faith and practice. -wiki-
Does scripture provide evidence that it is the sole (alone, without other) infallible (incapable of error) rule (plumb line) of faith (things salvific) and practice (faith in action)?
To be clear, this is to say that other things like pronouncements regarding salvation via Tradition or Popes, Patriarchs, and Pastors to the extent such pronouncement is not found in scripture are not necessary for salvation. For example, some will claim that one must submit to their Pope, Patriarch, or Pastor in order to be saved. Since that teaching is not in the bible, it is false based on the sola scriptura concept.
So, what does the bible have to say about it being all that's necessary for salvation?
Luke 1:1-4 Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word; It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus, That thou mightest know the certainty of those things, wherein thou hast been instructed.
Luke says I too will write things known by eyewitnesses so you will know with certainty what you believe. This statement eliminates other sources of information as even important to one's salvation.
John 20:31 But these [signs-of that which distinguished a person or thing from others-Vines] are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.
John says he wrote so you might believe unto salvation. How many readers believe the apostles left something out that is necessary for your salvation? Again, this statement is clearly telling us the apostles wrote all things necessary. As eyewitnesses, and guided by the Spirit, I wouldn't suggest to hint that they were fallible and left things to chance.
Acts 15:20 But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.
Things important, the apostles had recorded and preserved.
Romans 1:17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.
Did God fail to have His will and revelation written down? Did He have it written in any manner but correctly and accurately?
Romans 15:4 For whatsoever things were written aforetime were written for our learning, that we through patience and comfort of the scriptures might have hope.
Please note that Paul does not mention unwritten, oral Tradition spoken by such and such so-called infallible person as things necessary for our hope.
1 John 1:3-4 That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. And these things write we unto you, that your joy may be full [complete].
Please note the plural "we". We write what we witnessed to you that your joy may be complete. Again, this is scripture alone.
Jude 1:3 Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints.
Writing down about the common salvation once delivered. Hold on to it as they wrote it.
2 Peter 3:1-2 This second epistle, beloved, I now write unto you; in both which I stir up your pure minds by way of remembrance:That ye may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us the apostles of the Lord and Saviour:
In this Peter tells us the same thing to which Paul testifies.
Eph. 2:20 And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone;
All things necessary, being the foundation, are found written by the apostles and prophets.
So, these scriptures (and others) were written by apostles who tell us what sola scripture claims. Scripture is the infallible, sole rule of faith and practice. It is the plumb line for Christian faith and practice.