Acts 12:3-6

And because he saw it pleased the Jews, he proceeded further to take Peter also. (Then were the days of unleavened bread.) And when he had apprehended him, he put {him} in prison, and delivered {him} to four quaternions of soldiers to keep him; intending after Easter to bring him forth to the people. {Easter: Gr. Passover} {quaternions: a file of four soldiers} Peter therefore was kept in prison: but prayer was made without ceasing of the church unto God for him. {prayer...: or, instant and earnest prayer was made} And when Herod would have brought him forth, the same night Peter was sleeping between two soldiers, bound with two chains: and the keepers before the door kept the prison.