20 But turning around Peter sees the disciple whom Jesus loved following (that’s the one who reclined on His chest at the supper and said, “Lord, who is the one who is betraying you?”).
John 21:20 Cross References - WPNT
John 13:23-26
23 Now one of His disciples, whom Jesus loved, was reclining beside Jesus’ bosom.
24 So Simon Peter motions to him to inquire whom it might be that He was referring to.
25 And leaning back against Jesus’ breast he says to Him, “Lord, who is it?”
26 Jesus answers, “It is the one to whom I will give the piece of dunked bread.” And dunking the bread He gives it to Judas Iscariot, Simon’s son.
John 20:2
2 So she runs and comes to Simon Peter, and to the other disciple, whom Jesus loved, and says to them, “They have taken the Lord out of the tomb, and we don’t know where they put Him!”
John 21:7
7 Then that disciple whom Jesus loved says to Peter, “It’s the Lord!” Upon hearing that it was the Lord, Simon Peter tied on his outer garment (for he was stripped) and plunged into the sea.
John 21:24
24 This is the disciple who is testifying to these things, and who wrote them; and we know that his testimony is true.