John the Apostle
John 21:19BSB·traditional attribution

Jesus said this to indicate the kind of death by which Peter would glorify God. And after He had said this, He told him, “Follow Me.”

John Calvin Reformed @genevareformer

19. Signifying by what death he should glorify God. This circumlocution is highly emphatic; for though the end held out to all believers ought to be, to glorify God both by their life and by their death, yet John intended to employ a remarkable commendation for adorning the death of those who, by their blood, seal the Gospel of Christ and glorify his name, as...

Matthew Henry Presbyterian @wholebiblehenry

We have here Christ's discourse with Peter after dinner, so much of it as relates to himself, in which, I. He examines his love to him, and gives him a charge concerning his flock, Joh 21:15-17. Observe, 1. When Christ entered into this discourse with Peter.

Commenting on John 21:15-19

John Gill Reformed Baptist @doctorgill

This spake he,.... These are the words of the evangelist, explaining the meaning of Christ in like manner, as in Joh 12:33 signifying by what death he should glorify God; for by the above words Christ not only intimated that Peter should die, not a natural, but a violent death, or that he should die a martyr in his cause, but the very kind of...