(He said this to indicate the kind of death by which he would glorify God.) After this he said to him, "Follow me."
Peter turned and saw the disciple whom Jesus loved following them; he was the one who had reclined next to Jesus at the supper and had said, "Lord, who is it that is going to betray you?"
When Peter saw him, he said to Jesus, "Lord, what about him?"
Jesus said to him, "If it is my will that he remain until I come, what is that to you? Follow me!"
So the rumor spread in the community that this disciple would not die. Yet Jesus did not say to him that he would not die, but, "If it is my will that he remain until I come, what is that to you?"
References for John 21:23
This is the disciple who is testifying to these things and has written them, and we know that his testimony is true.
But there are also many other things that Jesus did; if every one of them were written down, I suppose that the world itself could not contain the books that would be written.