Acts 12:5,6

Peter therefore Till the day of his execution came; was kept in prison Under the continual guard of the fore-mentioned soldiers. But prayer without ceasing (The original expression, προσευχη εκτενης, signifies, earnest and importunate, as well as continual prayer;) was made of the church for him That is, for his deliverance, yet when their prayer was answered, they could scarce believe it, Acts 12:15. But why had they not prayed for James's deliverance also? Doubtless because he was put to death as soon as apprehended. And when Herod would have brought him forth For execution; the same night That is, the night before he had designed to do it; Peter was sleeping Easy and void of fear; between two soldiers, bound with two chains It is well known that this way of securing prisoners of consequence was practised among the Romans, as Grotius has shown in his note on Acts 28:16. One end of one chain was fastened to Peter's right hand, and the other end to the left arm of one of the soldiers; the other chain was, in like manner, fastened to Peter's left arm, and to the soldier's right arm; so that, humanly speaking, it was impossible he should have risen without immediately awaking them. And the keepers before the door The other two guards, then on duty, stood sentry before the prison doors, that there might be no attempt of any kind made to rescue him. So that he was sufficiently secured, to all human appearance. It is likely the Jews remembered how all the apostles had escaped, when they had formerly put them in prison; and, perhaps, they suspected the fidelity of the guards. It was, therefore, most probably at their request that such a number of soldiers were appointed to guard Peter. But though the persecutors thus showed themselves skilful in taking measures to destroy, they soon found, by experience, that no device can avail against any whom God is determined to preserve.