12:2 The James whom Herod executed was one of the sons of Zebedee, John’s brother.
12:3-5 Peter would have been guarded by four soldiers at a time, who worked three-hour shifts. The Sanhedrin may have recommended the heavy guard to Herod in light of their own experience attempting to jail the apostles (5:19).
12:12-16 Knowing that everyone inside was praying for Peter, Rhoda rushed back in to tell them that God had answered their prayers, not bothering to let Peter in first! Remarkably, they disbelieved her and suggested it was Peter’s angel. This reflected the common Jewish belief in guardian angels. It also shows how serious the persecutions had become, for it was believed that your guardian angel would sometimes appear shortly after your death. Thus it seems the crowd of believers was better prepared to believe Peter had been executed than that he had been released.
12:17 Peter went to another place most likely in an attempt to throw Herod and the Jewish authorities off his trail. God had freed him miraculously, but this did not mean Peter could flaunt his freedom or act imprudently. Peter instructed those present to tell James, Jesus’s brother, mentioned here for the first time in Acts. James, apparently not a follower of Jesus until after the resurrection (1Co 15:7), emerged as a leader in the Jerusalem church (Ac 15:13-21; Gl 1:19).
12:18-19 According to the Roman code of Justinian, soldiers who allowed a captive to escape would suffer the same penalty their charge was to suffer. Thus we see Peter was to be executed.
12:23 Herod died because he claimed for himself the honor and glory that belong only to God. There have been various speculations about the immediate cause of Herod’s death, including appendicitis, poisoning, and intestinal blockage.
12:24 With Herod out of the way, there were fewer hindrances to the spread of the good news, which flourished and multiplied.
12:25 Barnabas and Saul returned to Jerusalem after their relief mission. Here again we see the vital role Barnabas played in assimilating Saul into leadership of the early church.