John 21:20-22

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!”