What does Luke 22:59 mean?

This is Peter's third denial as recorded in Matthew, Mark, and Luke. He has already denied Jesus before a servant girl (Luke 22:57) and at least one man that another servant girl warned (Luke 22:58; Matthew 26:71–72; Mark 14:69–70). Now, warming himself before a fire surrounded by the temple guards and the high priest's servants, he is accused again, this time because of his accent.

John's account is key. He writes "One of the servants of the high priest, a relative of the man whose ear Peter had cut off, asked, 'Did I not see you in the garden with him?'" (John 18:26). At the garden, Peter had attempted to protect Jesus from arrest by drawing his sword and maiming a servant (John 18:10–11). Jesus healed the man and told Peter to put his sword away (Luke 22:49–51). Before Jesus and the disciples had retired to the garden, Jesus had warned Peter that he—and all the disciples—would turn away from Him. Peter vehemently denied it, saying he would die for Jesus. But Jesus told Peter he would deny Him three times this very night (Luke 22:31–34).

Peter couldn't imagine what circumstances could make him deny Jesus. John tells us. He is alone, first walking, then standing in the courtyard of the high priest, surrounded by the crowd of guards who had arrested Jesus. And right beside him is the cousin of the man he had attacked. He's not a soldier in a battle, surrounded by comrades. He's more like an untrained spy in enemy territory.

Luke says they recognize that Peter is a Galilean; Matthew 26:73 says Peter's accent gives him away. Certain Hebrew letters are pronounced with a deep, guttural sound. Galileans did not pronounce these as distinctly as Judaeans.