john 18:27 Peter then denied again: and immediately the cock crew. - Free Bible Online

      27. Peter then denied again--But, if the challenge of Malchus' kinsman was made simultaneously with this on account of his Galilean dialect, it was no simple denial; for Mt 26:74 says, "Then began he to curse and to swear, saying, I know not the man." So Mr 14:71. This was THE THIRD DENIAL.
      and immediately--"while he yet spake" (Lu 22:60).
      the cock crew--As Mark is the only Evangelist who tells us that our Lord predicted that the cock should crow twice (Mr 14:30), so he only mentions that it did crow twice (Mr 14:72). The other Evangelists, who tell us merely that our Lord predicted that "before the cock should crow he would deny Him thrice" (Mt 26:34; Lu 22:34; Joh 13:38), mention only one actual crowing, which was Mark's last. This is something affecting in this Evangelist--who, according to the earliest tradition (confirmed by internal evidence), derived his materials so largely from Peter as to have been styled his "interpreter," being the only one who gives both the sad prediction and its still sadder fulfilment in full. It seems to show that Peter himself not only retained through all his after-life the most vivid recollection of the circumstances of his fall, but that he was willing that others should know them too. The immediately subsequent acts are given in full only in Luke (Lu 22:61, 62): "And the Lord turned and looked upon Peter," from the hall of judgment to the court, in the way already explained. But who can tell what lightning flashes of wounded love and piercing reproach shot from that "look" through the eye of Peter into his heart! "And Peter remembered the word of the Lord, how He had said unto him, Before the cock crow, thou shalt deny Me thrice. And Peter went out and wept bitterly." How different from the sequel of Judas' act! Doubtless the hearts of the two men towards the Saviour were perfectly different from the first; and the treason of Judas was but the consummation of the wretched man's resistance of the blaze of light in the midst of which he had lived for three years, while Peter's denial was but a momentary obscuration of the heavenly light and love to his Master which ruled his life. But the immediate cause of the revulsion, which made Peter "weep bitterly," was, beyond all doubt, this heart-piercing "look" which his Lord gave him. And remembering the Saviour's own words at the table, "Simon, Simon, Satan hath desired to have you that he may sift you as wheat, but I have prayed [rather, 'I prayed'] for thee that thy faith fail not" (see on Lu 22:31, 32), may we not say that this prayer fetched down all that there was in that 'look' to pierce and break the heart of. Peter, to keep it from despair, to work in it "repentance unto salvation not to be repented of," and at length, under other healing touches, to "restore his soul?" (See on Mr 16:7).

JFB.