Matthew 26:34 - Ellicott's Commentary On The Whole Bible

Thou shalt deny me thrice. — The agreement of all the four Evangelists places the fact of the prediction beyond the shadow of a doubt, and the prevision which it implies is obviously more than a general insight into the instability of the disciple’s character, and involves a power essentially superhuman. We must not forget what the disciple could not fail to remember, that to the sin thus foretold was attached the penalty, that he who was guilty of it should be “denied before the angels of God” (Luke 12:9). That was the law of retribution, but as with all such laws, the penalty might be averted by repentance.