Acts 12:4-6

So when he had arrested him, he put him in prison, and delivered him to four squads of soldiers to keep him, intending to bring him before the people after Passover. Peter was therefore kept in prison, but constant prayer was offered to God for him by the church. And when Herod was about to bring him out, that night Peter was sleeping, bound with two chains between two soldiers; and the guards before the door were keeping the prison.