This is an allusion to what Jesus says in the New Testament. Here is the context. Throughout the gospels Jesus attempts to tell his disciples that he will die and rise again on the third day, but his disciples have a hard time understanding him. When he finally convinces his disciples, Peter, one of the most outspoken ones states he will follow Jesus no matter what, even to death. This is recorded in Matthew 26, Mark 13-14, and Luke 22.
At this juncture Jesus tells Peter that he will reject him three times before the rooster crows. Jesus words turn out to be truth. In fear, Peter rejects Jesus three times. Dejected Peter leaves and actually goes back to his former occupation, fishing. Jesus comes to Peter in John 21 and reinstates him. He gives Peter to chance to affirm his love three times.