Acts 12:3

The Feast of Unleavened Bread was a seven-day celebration that began on the day after Passover each spring. This was one of the three yearly feasts in Jerusalem that the Mosaic Law required all Jewish males to attend. As on the day of Pentecost (ch. 2), the city would have been swarming with patriotic Jews when Herod made his grandstand political move of arresting Peter. These Jews knew Peter as the leading apostle among the Christians and as a Jew who fraternized with Gentiles (ch. 10). This was the third arrest of Peter that Luke recorded (cf. Acts 4:3; Acts 5:18). Note that this persecution of the Christians did not arise from anything they had done but simply because Herod wanted to gain popularity with the Jews.