I Cor. 11:23: "..that which ALSO I [earlier] delivered unto you.." He tells the Corinthians he is presenting in writing what he had previously taught them orally.
2 Thes. 2:5: "Remember ye not, that, WHEN I WAS YET WITH YOU, I TOLD YOU THESE THINGS?" He gave them in writing what he had previously told them orally. He elaborates and provides further understanding in his writing to them.
2 Thes. 3:6: "When we were with you, this [same thing] we COMMANDED YOU [orally]...".
And yes, even Peter:
2 Peter 1:15: "Moreover I will endeavor that ye may AFTER MY DECEASE TO HAVE THESE THINGS ALWAYS IN REMEMBRANCE." Obviously, he was saying that he endeavored to put into writing what he had taught them earlier orally, so it would not be forgotten or corrupted after his death.
Excellent proof texts, good job! There is also:
I John 5:13
I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life.
John 21:24
This is the disciple who testifies to these things and who wrote them down. We know that his testimony is true.
John 20:31
But these are written that you may believe that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name.
I Corinthians 4:6
Now, brothers and sisters, I have applied these things to myself and Apollos for your benefit, so that you may learn from us the meaning of the saying, “Do not go beyond what is written.” Then you will not be puffed up in being a follower of one of us over against the other.
I Corinthians 12:11-12
These things happened to them as examples and were written down as warnings for us, on whom the culmination of the ages has come. So, if you think you are standing firm, be careful that you don’t fall!