St. Cyril of Alexandria (c. 424)
He suffers him no longer to be called Simon, exercising authority and rule over him already having become His own. By a title suitable to the thing, He changed his name into Peter, from the word 'petra' (rock); for on him He was afterwards to found His Church. (Cyril, T. iv. Comm. in Joan., p. 131)
He (Christ) promises to found the Church, assigning immovableness to it, as He is the Lord of strength, and over this He sets Peter as shepherd. (Cyril, Comm. on Matt., ad loc.)
Therefore, when the Lord had hinted at the disciple's denial in the words that He used, 'I have prayed for thee that thy faith not fail,' He at once introduced a word of consolation, and said (to Peter): 'And do thou, when once thou art converted, strengthen thy brethren.' That is, 'Be thou a support and a teacher of those who through faith come to me.' Again, marvel also at the insight of that saying and at the completeness of the Divine gentleness of spirit. For so that He should not reduce the disciple to despair at the thought that after his denial he would have to be debarred from the glorious distinction of being an Apostle, He fills him with good hope, that he will attain the good things promised. ...O loving kindness! The sin was not yet committed, and He already extends His pardon and sets him (Peter) again in his Apostolic office. (Cyril Comm. on Luke's Gospel)
For the wonderous Peter, overcome by uncontrollable fear, denied the Lord three times. Christ heals the error done, and demands in various ways the threefold confession ... For although all the holy disciples fled, ...still Peter's fault in the threefold denial was in addition, special and peculiar to himself. Therefore, by the threefold confession of blessed Peter, the fault of the triple denial was done away. Further, by the Lord's saying, Feed my lambs, we must understand a renewal as it were of the Apostleship already given to him, washing away the intervening disgrace of his fall, and the littleness of human infirmity. (Cyril, Comm. on John's Gospel).
They (the Apostles) strove to learn through one, that preeminent one, Peter. (Cyril, Ib. 1. ix. p. 736).
And even blessed Peter, though set over the holy disciples, says 'Lord, be it far from Thee, this shall be done to Thee. (Cyril, Ibid. 924).
If Peter himself, that prince of the holy disciples, was, upon an occassion, scandalized, so as suddenly to exclaim, 'Lord, be it far from Thee,' what wonder that the tender mind of woman should be carried away? (Cyril, Ibid, p. 1064)
That the Spirit is God we shall also learn hence. That the prince of the Apostles, to whom 'flesh and blood,' as the Savior says, 'did not reveal' the Divine mystery, says to Ananias, 'Why hath Satan tempted thy heart, (Cyril, T. v. Par. 1. Thesaur. p. 340)
Besides all these, let there come forward that leader of the holy disciples, Peter, who, when the Lord, on a certain occassion, asked him, 'Whom do men say that the Son of man is?' instantly cried out, 'Thou art the Christ, the Son of the living God.' (Cyril, T. v. P.2, Hom. viii. De Fest. Pasch. p. 105)
'If I wash thee not, thou shalt have no part with me.' When the Coryphaeus (Peter) had heard these words, he began to change. (Cyril, Ib. Hom.)
This bold man (Julian), besides all this, cavils at Peter, the chosen one of the holy Apostles. (Cyril, T. vi.l. ix. Contr. Julian. p. 325).