John 13:38

Jesus answered him, wilt thou lay down thy life for my
sake
Christ speaks these words as questioning, not Peter's sincerity, but his strength; or as deriding him, or rather pitying him; as if he should say, thou poor vain self-sufficient man, thou dost not know what thou talkest of:

verily, verily, I say unto thee, the cock shall not crow, till thou
hast denied me thrice;
not that Peter should deny him three times, before the cock crowed once; for certain it is, that Peter denied Christ but once, before the cock crew, ( Mark 14:68 ) ; but the meaning is, that before the cock had, lone crowing, or within the time of cock crowing, he should deny him thrice: whence it follows, that there is no necessity of concluding from hence, that this night was the passover night, and the night in which Judas betrayed Christ, and Peter denied him, but was two nights before; and therefore it is not said here, as by the other evangelists, "this day", or "this night", or "this day, even this night thou shalt deny me"; only in general before the cock crow, or within the time of cock crowing: so that it appears, that Peter twice expressed his confidence, in laying down his life for Christ; once at the supper in Simon's house at Bethany, two days before the "passover", and again at the passover supper in Jerusalem; and as often Christ rebuked his confidence by this expression, only varying it as the different times required, and therein gave a full proof of his omniscience.