Acts 12:1-6 (ESV)
About that time Herod the king laid violent hands on some who belonged to the church. He killed James the brother of John with the sword, and when he saw that it pleased the Jews, he proceeded to arrest Peter also. This was during the days of Unleavened Bread. And when he had seized him, he put him in prison, delivering him over to four squads of soldiers to guard him, intending after the Passover to bring him out to the people. So Peter was kept in prison, but earnest prayer for him was made to God by the church.
Now when Herod was about to bring him out, on that very night, Peter was sleeping between two soldiers, bound with two chains, and sentries before the door were guarding the prison.
English Standard Version (ESV)
The Holy Bible, English Standard Version Copyright © 2001 by Crossway Bibles, a publishing ministry of Good News Publishers.