John 21:20 in the King James Version
Then Peter, turning about, seeth the disciple whom Jesus loved following; which also leaned on his breast at supper, and said, Lord, which is he that betrayeth thee?
Context
19 Now he said this, signifying by what kind of death he would glorify God. When he had said this, he said to him, “Follow me.”
20 Then Peter, turning around, saw a disciple following. This was the disciple whom Jesus loved, the one who had also leaned on Jesus’ chest at the supper and asked, “Lord, who is going to betray you?”
21 Peter, seeing him, said to Jesus, “Lord, what about this man?”