Skeptics and critics have claimed the gospels contradict about Peter’s denials rooster crowing in regard to Jesus’ prediction. Did Jesus predict one or two rooster crowings? Were there one or two rooster crows? Here is the alleged “contradiction”:

What did Jesus say about Peter’s denial?
(a) “The cock will not crow till you have denied me three times” (John 13:38).
(b) “Before the cock crows twice you will deny me three times” (Mark 14:30). When the cock crowed
once, the three denials were not yet complete (see Mark 14:72). Therefore prediction (a) failed.

All four gospels report Jesus’ prediction of Peter’s three denials of Jesus  (Matthew 26:34; Mark 14:30; Luke 22:34; John 13:38), and Peter’s actual three denials of Jesus, including his vehemently denying that he even knew who Jesus was (Matthew 26:69-75; Mark 14:60-72; Luke 22:54-62; John 18:15-18, 25-27). 

The difference is that in Matthew, Luke and John, Jesus is recorded as saying, “before a rooster crows, you will deny me three times” (Matthew 26:34 NASB); “a rooster will not crow today, before you may disown knowing Me three times” (Luke 22:34 LSV); “a rooster will not crow until you have denied me three times” (John 13:38 NASB).

However, in Mark’s gospel, Jesus is recorded as saying, “before a rooster crows twice, you yourself will deny me three times” (Mark 14:30 NASB). Critics allege a contradiction, therefore, between the gospels of Matthew, Luke and John with Mark, about whether there would be one or two rooster crows after Peter’s denials.  

Here is Mark’s account of the denials:

“While Peter was below in the courtyard, one of the slave women of the high priest came, and seeing Peter warming himself, she looked at him and said, ‘You were with Jesus the Nazarene as well.’ But he denied it, saying, ‘I neither know nor understand what you are talking about.’ And he went out onto the porch. The slave woman saw him, and began once more to say to the bystanders, ‘This man is one of them!’ But again he denied it. And after a little while the bystanders were again saying to Peter, ‘You really are one of them, for you are a Galilean as well.’ But he began to curse himself and to swear, ‘I do not know this man of whom you speak!’And immediately a rooster crowed a second time. And Peter remembered how Jesus had made the remark to him, ‘Before a rooster crows twice, you will deny Me three times.’ And he hurried on and began to weep”—Mark 14:60-72 NASB

How can this apparent “contradiction” be explained? Mark was a close associate of Peter through the years (1 Peter 5:13) and provided a fuller, more detailed account of these events; hence, ‘two denials’, rather than one. The main thing is that a rooster did crow after Peter’s three denials, and he then got the point that he was overconfident, in spite of Jesus’ prediction. The other three gospels are simply just not quite as detailed on this point, but they nevertheless record the main facts. 

Thus, upon close examination, the gospels do not contradict about Peter’s denials and rooster crowing. The four gospels combined preserve for us “an accurate account” of the events of Jesus’ life (Luke 1:3 NLT).