John Calvin Commentary John 13:38

"Jesus answereth, Wilt thou lay down thy life for me? Verily, verily, I say unto thee, The cock shall not crow, till thou hast denied me thrice." — John 13:38 (ASV)

Wilt thou lay down thy life for me? Christ did not choose to debate with Peter, but wished for him to grow wise by his own experience, like fools, who never grow wise until they have received a blow. Peter promises unshaken firmness, and indeed expresses the sincere conviction of his mind; but his confidence is full of rashness, for he does not consider what strength has been given to him. Now since this example belongs to us, let each of us examine his own defects, so that he may not be swelled with vain confidence. We cannot indeed make too large promises about the grace of God; but what is reproved here is the arrogant presumption of the flesh, for faith rather produces fear and anxiety.

The cock will not crow. As presumption and rashness proceed from ignorance of ourselves, Peter is blamed for pretending to be a valiant soldier while he is beyond arrow-shot; for he has not yet tested his strength, and imagines that he could do anything. He was afterwards punished, as he deserved, for his arrogance. Let us learn to distrust our own strength, and to turn quickly to the Lord, so that he may support us by his power.