John Gill Commentary Mark 14:30

"And Jesus saith unto him, Verily I say unto thee, that thou to-day, [even] this night, before the cock crow twice, shalt deny me thrice." — Mark 14:30 (ASV)

And Jesus says to him, verily I say to you As confident as you are of standing by me, and abiding with me; that this day, which was then begun; for the Jews reckoned their days from evening, as in (Genesis 1:5); even in this night; this night to be observed, this night of the passover, before it is past: before the cock crow twice; for there was a first and second cock crowing, the one at midnight, and the other near break of day, and which last is properly the cock crowing: the word "twice" is left out in the Ethiopic version: you shall deny me thrice; as he did; (See Gill on Matthew 26:34).