Peter's confident promise exceeds his present strength.

John 13:36–38

³⁶Simon 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.

³⁷Peter said unto him, Lord, why cannot I follow thee now? I will lay down my life for thy sake.

³⁸Jesus 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.