John 21:20-24

Peter turned and saw the disciple whom Jesus loved following them; the one who also had leaned back on His chest at the supper and had said, “Lord, who is it that is going to betray You?” So when Peter saw him, he asked Jesus, “Lord, and what about this man [what is in his future]?” Jesus said to him, “If I want him to stay alive until I come [again], what is that to you? You follow Me!” So this word went out among the brothers that this disciple (John) was not going to die; yet Jesus did not say to him that he was not going to die, but only, “If I want him to stay alive until I come [again], what is that to you?” This is the same disciple who is testifying to these things and has recorded them; and we know [without any doubt] that his testimony is true.