Simon Peter said unto him, Lord, whither goest thou? Jesus answered him, Whither I go, thou canst not follow me now; but thou shalt follow me afterwards. (37) Peter said unto him, Lord, why cannot I follow thee now? I will lay down my life for thy sake. (38) Jesus answered him, Wilt thou lay down thy life for my sake? Verily, verily, I say unto thee, The cock shall not crow, till thou hast denied me thrice.
For the observations on the fall of Peter, and the Lord's recovery of him by his grace. See Luke 22:31 and the Commentary.