John 13:36

The Word, however, departs on his own courses, and he who follows the Word follows him. But one who is not prepared to walk in his steps persistently cannot follow, since the Word leads those to his Father who do all things that they might be able to follow him and that they may follow him until they may say to the Christ, "My soul has clung to you."

Therefore, he prudently asks to be drawn, because not everyone can follow. Finally, when Peter said, "Where are you going?" the Word of God answered, "You cannot follow me now, but you will follow later" (John 13:36). He entrusted the keys of the kingdom of heaven to her and considered her equal by following him. However, he did not delay this soul; because she did not presume, but she asked.

(Hom. lxxiii. 3) Great is love, and stronger than fire; nothing can stop its course. Peter the most ardent of all, as soon as he hears our Lord say, Whither I go ye cannot follow Me now, asks, Lord, whither goest Thou?

A great thing is love, and stronger than fire itself, and it goeth up to the very heaven; there is no hindrance which can restrain its tearing force. And so the most fervent Peter, when he hears, "Whither I go ye cannot come," what saith he? "Lord, whither goest thou?" and this he said, not so much from wish to learn, as from desire to follow. To say openly, "I go," he dared not yet, but, "Whither goest thou?" Christ answered, not to his words, but to his thoughts. For that this was his wish, is clear from what Christ said, "Whither I go thou canst not follow Me now." Seest thou that he longed for the following Him, and therefore asked the question? And when he heard, "thou shalt follow Me afterwards" not even so did he restrain his longing, and, though he had gained good hopes, he is so eager as to say, "Why cannot I follow Thee now? I will lay down my life for Thee."

(Tr. lxvi. 1) The disciple asks this, as if he were ready to follow. But our Lord saw his heart; Jesus answered him, Whither I go, thou canst not follow Me now; He checks his forwardness, but does not destroy his hope; nay, confirms it; But thou shalt follow Me afterwards. Why hastenest thou, Peter? The Rock has not yet established thee with His spirit. Be not lifted up with presumptions, thou canst not now; be not cast down with despair, thou shalt follow Me afterwards.

While the Lord Jesus was commending to the disciples that holy love wherewith they should love one another, "Simon Peter saith unto Him, Lord, whither goest Thou?" So, at all events, said the disciple to his Master, the servant to his Lord, as one who was prepared to follow. Just as for the same reason the Lord, who read in his mind the purpose of such a question, made him this reply: "Whither I go, thou canst not follow me now;" as if He said, In reference to the object of thy asking, thou canst not now. He does not say, Thou canst not; but "Thou canst not now." He intimated delay, without depriving of hope; and that same hope, which He took not away, but rather bestowed, in His next words He confirmed, by proceeding to say, "Thou shall follow me afterwards." Why such haste, Peter? The Rock (petra) has not yet solidified thee by His Spirit. Be not lifted up with presumption, "Thou canst not now;" be not cast now into despair, "Thou shalt follow afterwards."

Simon Peter saith unto Him, Lord, whither goest Thou?

Peter again with his usual curiosity is anxious to learn more, and busies himself about the significance of Christ's words, not yet (as seems probable) comprehending the real meaning of what had been said, yet feeling with all the force of his fiery zeal that it was his duty to follow Christ. And in this matter most admirable is the behaviour of the disciples. For certainly no one would allow that it was only the chief disciple who was in ignorance while the others fully understood the matter, and that this was why he asked the question. I should rather say that they yielded to him, as chief among them, the privilege of speaking first, and of taking the initiative in courageous inquiry. For the speaking into the ears of their Master was no light and easy matter, even for those who were reputed to be somewhat. And the conduct of Peter is no less admirable, who is harassed by no fear of being thought sluggish in the comprehension of those matters of which he was ignorant, but zealously seeks for enlightenment, considering that the profit he will derive from gratifying his love of knowledge will be of more value than an unseasonable sense of shame: and so in this also he is a pattern to those that live after him. For we ought never, I think, to pass over the words of our teachers, even though they may not be so very distinct, merely for the sake of seeming to be shrewd people and very quick in intelligence; but rather to investigate the meaning and search it out wisely, in the teaching at first delivered to us for our profit. For the knowledge of what is useful is far nobler than a vain semblance of wisdom, and far better is it to learn a thing in reality than merely to seem to know all about it.

The disciples had not yet been clothed with the power from on high, neither had they received the strength that was to invigorate them and impart courage to their character—I mean the gift of the Holy Spirit. Thus, they were not able to wrestle with death and engage in a conflict with terrors so hard to face.

Peter, having become bold from great fervor, when he heard the Lord say "where I am going, you cannot come," asks: "Where are You going?" He speaks to Christ as if to say: "What kind of path is this that I cannot travel?" He asks this not so much wishing to learn where He is going, as covertly expressing the thought that even if You were to go by the most difficult path of all, I would still follow You. So much did he love always being together with Christ!
Therefore Christ also answers Peter's thought: "You cannot follow Me now, but afterward you will follow Me."

Simon Peter saith unto him. Here the fourth point is touched upon, namely the repression of Peter's presumption, by which he was offering himself to imitate the Lord. Therefore Peter asks him, so as to offer himself: Lord, whither goest thou? And because he wished to offer himself, the Lord shows him his own incapacity, lest he burst forth in words: Jesus saith unto him: Whither I go, thou canst not follow me now, on account of weakness: but thou shalt follow me afterwards, when strengthened by virtue. But Peter is not swayed by the admonition.

Above, John mentioned the defection of one of the disciples, Judas the traitor; here he tells of the failure of another, Peter, who denied Christ. First we see the occasion of Christ's prediction; secondly, the prediction of Peter's denial. He does two things about the first: he mentions Peter's desire; secondly, his confidence, Why cannot I follow you now? He does two things about the first: he shows Peter expressing his desire; secondly, he shows that its fulfillment will be delayed, you cannot follow me now.

Peter's desire is shown by the quick way he questioned Christ: Simon Peter said to him, Lord, where are you going? Peter had heard our Lord say that he would be with them just for a little while, and he became anxious about Christ's leaving them. So he asks, Where are you going? Chrysostom says about this: "Peter's love was indeed great, and more furious than a fire that nothing could stop." This is why even after Christ had said, "Where I am going you cannot follow," Peter still wanted to follow him. So he asked where he was going, just like we read in the Song of Songs: "Whither has your beloved gone, O fairest among women? Whither has your beloved turned, that we may seek him with you?" (6:1).

Yet he cannot now have what he desires, since for the present he is prevented from following Christ. Where I am going you cannot follow me now; but you shall follow afterward. This is like saying: You are still imperfect, and thus not able to follow me now; but later, when you are perfect, you will follow me. This is similar to what we will read further on: "Truly, truly, I say to you, when you were young," that is, imperfect, "you girded yourself...but when you are old," and have climbed the mountain of perfection, "you will stretch out your hands, and another will gird you" (21:18).