John 21:7; John 21:20; John 21:24
Therefore the disciple, the one Jesus loved, said to Peter, "It is the Lord!" When Simon Peter heard that it was the Lord, he tied his outer garment around him (for he was stripped) and plunged into the sea.
So Peter turned around and saw the disciple Jesus loved following them. [That disciple] was the one who had leaned back against Jesus at the supper and asked, "Lord, who is the one that's going to betray You?"
This is the disciple who testifies to these things and who wrote them down. We know that his testimony is true.