By what death ... - In these words two things are implied:

1. that Peter would die a violent death; and,

2. that his death would be such as to honor God.

The ancients say that Peter was crucified at Rome, about 34 years after this, with his head downward. Clemens says that he was led to the crucifixion with his wife, and sustained her in her sufferings by exhorting her to remember the example of her Lord. He also adds that he died, not as the philosophers did, but with a firm hope of heaven, and patiently endured the pangs of the cross (Strom. vii.). This declaration of the Saviour was doubtless continually before the mind of Peter, and to the hour of his death he maintained the utmost constancy and fidelity in his cause, thus justifying the appellation which the Lord Jesus gave him - a rock.

Should glorify God - Ancient writers state that, about thirty-four years after this, Peter was crucified; and that he deemed it so glorious a thing to die for Christ that he begged to be crucified with his head downwards, not considering himself worthy to die in the same posture in which his Lord did. So Eusebius, Prudentius, Chrysostom, and Augustin. See Calmet.

Follow me - Whether our Lord meant by these words that Peter was to walk with him a little way for a private interview, or whether he meant that he was to imitate his example, or be conformed to him in the manner of his death, is very uncertain.

This spake he,.... These are the words of the evangelist, explaining the meaning of Christ in like manner, as in John 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 death he should die, namely, by crucifixion; and that Peter was crucified at Rome, ecclesiastical history confirms (f), when Christ was magnified, and God was glorified by his zeal and courage, faith and patience, constancy and perseverance to the end:

and when he had spoken this: concerning the usage and treatment he should meet with, the sufferings he should undergo, and death he should die for his sake, for the present trial of him:

he saith unto him, follow me: which may be understood literally, Jesus now rising up, and ordering him to come after him; and yet as a sign of his following him, in a spiritual sense, exercising every grace upon him, discharging every duty towards him, faithfully and constantly performing his work and office, as an apostle and preacher of the Gospel, in which he had now reinstated and confirmed him, and patiently bearing and suffering all kind of reproach, persecution, and death, for his name's sake.

(f) Euseb. Eccl. Hist. l. 2. c 25.

By what death (ποίῳ)

Properly, by what manner of death. So Rev.

This spake he, signifying by {f} what death he should glorify God. And when he had spoken this, he saith unto him, Follow me.

(f) That is, that Peter would die by a violent death.

21:19 By what death he should glorify God. These two verses can only be understood as declaring that Peter should die the death of a martyr. John wrote after Peter's death, and may be understood as affirming that he did thus glorify God. The universal testimony of the ancient Church is that he did thus die. It is asserted that Peter was crucified, a fact that is probable, as he was not a Roman citizen.

Follow me. He had once forsaken Christ through fear of death. Now, with a prospect of violent death before him, he is bidden to resume the Master's work and to follow him. He did this, from this time, faithfully.

21:19 By what death he should glorify God - It is not only by acting, but chiefly by suffering, that the saints glorify God. Follow me - Showing hereby likewise what death he should die.

19. This spake he, signifying by what death he should glorify God-not, therefore, a mere prediction of the manner of his death, but of the honor to be conferred upon him by dying for his Master. And, indeed, beyond doubt, this prediction was intended to follow up his triple restoration:-"Yes, Simon, thou shall not only feed My lambs, and feed My sheep, but after a long career of such service, shalt be counted worthy to die for the name of the Lord Jesus."

And when he had spoken this, he saith unto him, Follow me-By thus connecting the utterance of this prediction with the invitation to follow Him, the Evangelist would indicate the deeper sense in which the call was understood, not merely to go along with Him at that moment, but to come after Him, "taking up his cross."

21:15-19 Our Lord addressed Peter by his original name, as if he had forfeited that of Peter through his denying him. He now answered, Thou knowest that I love thee; but without professing to love Jesus more than others. We must not be surprised to have our sincerity called into question, when we ourselves have done that which makes it doubtful. Every remembrance of past sins, even pardoned sins, renews the sorrow of a true penitent. Conscious of integrity, Peter solemnly appealed to Christ, as knowing all things, even the secrets of his heart. It is well when our falls and mistakes make us more humble and watchful. The sincerity of our love to God must be brought to the test; and it behoves us to inquire with earnest, preserving prayer to the heart-searching God, to examine and prove us, whether we are able to stand this test. No one can be qualified to feed the sheep and lambs of Christ, who does not love the good Shepherd more than any earthly advantage or object. It is the great concern of every good man, whatever death he dies, to glorify God in it; for what is our chief end but this, to die to the Lord, at the word of the Lord?