MATTHEW 26:34 (cf. Mark 14:30)—When Peter denied Christ, did the rooster crow once or twice?
PROBLEM: Matthew and John (13:38) say before the rooster crows once, Peter will have denied the Lord three times. But Mark affirms that before the rooster crows twice Peter will deny Christ three times. Which account is right?
SOLUTION: There is no contradiction between the two accounts because, given the correctness of the text, Matthew and John do not expressly state how many times the rooster will crow. They simply say Peter will deny Christ three times “before the rooster crows,” but they do not say how many times it will crow. Mark may simply be more specific, affirming exactly how many times the rooster would crow.
It is also possible that different accounts are due to an early copyist error in Mark, that resulted in the insertion of “two” in early manuscripts (at Mark 14:30 and 72). This would explain why some important manuscripts of Mark mention only one crowing, just like Matthew and John, and why “two” appears at different places in some manuscripts.
Geisler, N. L., & Howe, T. A. (1992). When critics ask : A popular handbook on Bible difficulties (359). Wheaton, Ill.: Victor Books.