Albert Barnes on Matthew 26:33

Peter answered--though all, etc. The word men is improperly inserted here by the translators. Peter meant only to affirm this of the disciples. This confidence of Peter was entirely characteristic. He was ardent, sincere, and really attached to his Master. Yet this declaration was made, evidently:

(1.) From true love to Jesus.

(2.) From too much reliance on his own strength.

(3.) From ignorance of himself, and of the trials which he was soon to pass through. And it most impressively teaches us: (1.) That no strength of attachment to Jesus can justify such confident promises of fidelity, made without dependence on him.

(2.) That all promises to adhere to him, should be made relying on him for aid.

(3.) That we little know how feeble we are, till we are tried.

(4.) That Christians may be left to great and disgraceful sins to show them their weakness. Luke adds, that Jesus said to Peter, that Satan had desired to have him, that he might sift him as wheat; that he might thoroughly try him. But Jesus says that he had prayed for him, that his faith should not fail, and charged him when he was converted, i.e., when he was turned from this sin, to strengthen his brethren, i.e., by teaching them to take warning by his example. Lk 22:31-33.