John Calvin on Acts 12:5

5. But prayers were made. Luke teacheth here that the faithful did not, in the mean season, foreslow [neglect] their duty, Peter stood in the forward “In prima acie,” in the front rank, the van. alone; but all the rest fought with their prayers together with him, and they aided him so much as they were able. Hereby we do also gather, that they were not discouraged, for by prayer they testify that they persist so much as they are able in defense of the cause, for which Peter is in danger of life. This place teacheth, first, how we ought to be affected when we see our brethren persecuted by the wicked for the testimony of the gospel, for if we be slothful, and if we be not inwardly touched with their dangers, we do not only defy and them of the due duty of love, but also treacherously forsake the confession of our faith; and, assuredly, if the cause be common, yea, if they fight for our safety and salvation, we do not only forsake them, but even Christ and ourselves; and the present necessity requireth, that they be far more fervent in prayer than commonly they are, whosoever will be counted Christians. We see some of our brethren (being brought to extreme poverty) live in exile, others we see imprisoned, many cast into stinking dungeons, many consumed with fire, yea, we see new torments oftentimes invented, whereby being long tormented they may feel death. Unless these provocations sharpen our desire to pray, we be more than blockish; therefore, so soon as any persecution ariseth, let us by and by get ourselves to prayer.

Also, it is a likely thing that the Church took greater thought for Peter’s life, because they should have suffered great loss if he had gone. “In ejus morte,” in his death. Neither doth Luke say barely that prayer was made; but he addeth also, that it was earnest and continual, whereby he giveth us to understand that the faithful prayed not coldly or over fields; “Defunctorie,” perfunctorily. but so long as Peter was in the conflict, the faithful did what they could to help him, and that without wearisomeness. We must always understand the name of God, which is here expressed, whensoever mention is made of prayer in the Scripture, for this is one of the chiefest and first principles of faith, that we ought to direct our prayers unto God alone, as he challengeth to himself this peculiar worship, “Call upon me in the day of tribulation,” (Psalm 50:15.)

Acts 12:6-11

6. And when Herod was about to bring him forth, the same night slept Peter between two soldiers, bound with two chains; and the keepers kept the prison before the door. 7. And, behold, the angel of the Lord stood, and a light shined in the habitation: and he smote Peter’s side, saying, Arise straightway; and his chains felt from his hands, 8. And the angel said to him, Gird thyself, and bind on thy sandals. And he did so. Then he saith to him, Put thy garment about thee, and follow me. 9. And going out, he followed him, neither understood he that that was true which was done by the angel; but he thought that he saw a vision. 10. And when they were past the first watch, and the second, they came to the iron gate, which leadeth into the city, which opened to them of its own accord; and when they were come out, they passed through one street, and by and by the angel departed from him. 11. Then Peter returning to himself, said, Now of a truth I know that the Lord hath sent his angel, and hath delivered me out of the hand of Herod, and from all the waiting of the people of the Jews.