Peter proclaimed “Jesus resurrected” to crowds of Jews with stones. This is relevant because as all the apostles knew, their lives were at risk in proclaiming this to the Jews.
c. A.D. 110, Ignatius of Antioch reported that Peter bet his life on Jesus's having resurrected.1 This is relevant because Ignatius's beliefs about the apostles' deaths were warranted.
Peter did end up dying for his faith. (We know this because most/all the apostles died over their belief in Jesus's resurrection, and because early Christians c. A.D. 70-200 all confidently believed he did1). Peter's dying for his faith is relevant because it confirms that Peter had been preaching and performing the above acts in an environment which was lethal, and it did end up killing him.