Acts 12:5

We have here an account of Peter's deliverance out of prison, by which the design of Herod against him was defeated, and his life preserved for further service, and a stop given to this bloody torrent. Now, I. One thing that magnified his deliverance was that it was a signal answer to prayer (Act 12:5): Peter was kept in prison with a great deal of care, so that it was altogether impossible, either by force or by stealth, to get him out. But prayer was made without ceasing of the church unto God for him, for prayers and tears are the church's arms; therewith she fights, not only against her enemies, but for her friends: and to these means they have recourse. 1. The delay of Peter's trial gave them time for prayer. It is probable that James was hurried off so suddenly and so privately that they had not time to pray for him, God so ordering it that they should not have space to pray, when he designed they should not have the thing they prayed for. James must be offered upon the sacrifice and service of their faith, and therefore prayer for him is restrained and prevented; but Peter must be continued to them, and therefore prayer for him is stirred up, and time is given them for it, by Herod's putting off the prosecution. Howbeit, he meant not so, neither did his heart think so. 2.

— Matthew Henry's Concise Commentary (public domain)

prayer was made without ceasing--rather, "instant," "earnest," "urgent" (Margin); as in Luk 22:44; Act 26:7; and Pe1 4:8 (see Greek). of the church unto God for him--not in public assembly, for it was evidently not safe to meet thus; but in little groups in private houses, one of which was Mary's (Act 12:12). And this was kept up during all the days of unleavened bread.

— Jamieson-Fausset-Brown Commentary (public domain)