When Jesus was arrested on Good Friday, He was taken to the Sanhedrin. Saint Peter was the only Apostle that went there to be close to Him. The others did not go, most likely out of fear. Peter was probably afraid too, yet He couldn’t stay away from His Lord. We learn of this account in the Gospel of Matthew:
Now Peter was sitting outside in the courtyard. And a maid came up to him, and said, “You also were with Jesus the Galilean.” But he denied it before them all, saying, “I do not know what you mean.” And when he went out to the porch, another maid saw him, and she said to the bystanders, “This man was with Jesus of Nazareth.” And again he denied it with an oath, “I do not know the man.” After a little while, the bystanders came up and said to Peter, “Certainly you are also one of them, for your accent betrays you.” Then he began to invoke a curse on himself and to swear, “I do not know the man.” And immediately the cock crowed. And Peter remembered the saying of Jesus, “Before the cock crows, you will deny me three times.” And he went out and wept bitterly.
Like us, Peter was human. Even though he was a devout follower of Jesus, in a moment of fear and weakness, he was tempted and made a wrong choice. We know he regretted it immediately after because of the way we read that he “remembered the saying of Jesus,” and how he went out and wept bitterly.