68 But he denied it, saying, "I neither know nor understand what you are saying." And he went out on the porch, and a rooster crowed. 69 And the servant girl saw him again, and began to say to those who stood by, "This is one of them." 70 But he denied it again. And a little later those who stood by said to Peter again, "Surely you are one of them; for you are a Galilean, and your speech shows it." 71 Then he began to curse and swear, "I do not know this Man of whom you speak!" 72 A second time the rooster crowed. Then Peter called to mind the word that Jesus had said to him, "Before the rooster crows twice, you will deny Me three times." And when he thought about it, he wept.
Matthew Henry's Commentary on Mark 14:68-72
Commentary on Mark 14:66-72
(Read Mark 14:66-72)
Peter's denying Christ began by keeping at a distance from him. Those that are shy of godliness, are far in the way to deny Christ. Those who think it dangerous to be in company with Christ's disciples, because thence they may be drawn in to suffer for him, will find it much more dangerous to be in company with his enemies, because there they may be drawn in to sin against him. When Christ was admired and flocked after, Peter readily owned him; but will own no relation to him now he is deserted and despised. Yet observe, Peter's repentance was very speedy. Let him that thinketh he standeth take heed lest he fall; and let him that has fallen think of these things, and of his own offences, and return to the Lord with weeping and supplication, seeking forgiveness, and to be raised up by the Holy Spirit.