Sola Scriptura: 2. Proof

My friend wrote:

Show me Sola Scriptura in Scripture and I will believe it...

With this statement, he was asking for scriptural proof for sola Scriptura. My first response is to cite 2 Timothy 3:16-17 (which I incorrectly identified as 1 Timothy 3:16-17 on his Facebook page).

How is this passage a proof for sola Scriptura in the way that I have argued the doctrine must be defined?

Notice, especially, what 2 Tim 3:17 says about Scripture: "that the man of God may be thoroughly equipped for every good work."

How equipped does Scripture make the man of God? THOROUGHLY EQUIPPED. (Other translations render this phrase, "perfect" or "complete.")

For what is the man of God thoroughly equipped by the Scriptures? EVERY GOOD WORK.

Notice, also, that no similar statement is made by the Scriptures for any other possible source of authority.

And so the inevitable conclusion is that Scripture alone is the only the sufficient, final arbiter of all disputes concerning matters of life and godliness.