John 21:20-23

Then Peter turned and saw that the disciple whom Jesus loved was following them. (This was the disciple who sat close to Jesus at the Last Supper and had asked him, “Lord, who is the one that will betray you?”) So when Peter saw him, he asked Jesus, “What’s going to happen to him?” Jesus replied, “If I decide to let him live until I return, what concern is that of yours? You must still keep on following me!” So the rumor started to circulate among the believers that this disciple wasn’t going to die. But Jesus never said that, he only said, “If I let him live until I return, what concern is that of yours?”