Acts 12:1-9 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. And behold, an angel of the Lord stood next to him, and a light shone in the cell. He struck Peter on the side and woke him, saying, “Get up quickly.” And the chains fell off his hands. And the angel said to him, “Dress yourself and put on your sandals.” And he did so. And he said to him, “Wrap your cloak around you and follow me.” And he went out and followed him. He did not know that what was being done by the angel was real, but thought he was seeing a vision.
ESV: English Standard Version 2016