Jamieson, Fausset and Brown on Acts 12:5-6

5-6. prayer was made without ceasing--rather, "instant," "earnest," "urgent" (Margin); as in Lu 22:44; Ac 26:7; and 1Pe 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 (Ac 12:12). And this was kept up during all the days of unleavened bread.