Read John 18:25-27

Again Peter denied [knowing Jesus]. And immediately a rooster crowed. - John 18:27 (NLT)

Pruning hurts, at least at first. Even though Jesus had predicted it to Peter, he still denied knowing Jesus three times. The crowing of the rooster brought Jesus’ words back to Peter, and he was devastated. But we will see later that he was moved not to despair, but to repentance. This is an example of how Law and Gospel are used together by God to strengthen our faith and prepare us for (more) service.