The night before Herod was to bring him to trial, Peter was sleeping between two soldiers, bound with two chains,1 and sentries stood guard at the entrance.
Suddenly an angel2 of the Lord appeared and a light shone in the cell. He struck Peter on the side and woke him up. "Quick, get up!" he said, and the chains fell off Peter's wrists.3
Then the angel said to him, "Put on your clothes and sandals." And Peter did so. "Wrap your cloak around you and follow me," the angel told him.
Peter followed him out of the prison, but he had no idea that what the angel was doing was really happening; he thought he was seeing a vision.4
They passed the first and second guards and came to the iron gate leading to the city. It opened for them by itself,5 and they went through it. When they had walked the length of one street, suddenly the angel left him.
References for Acts 12:10
Then Peter came to himself6 and said, "Now I know without a doubt that the Lord sent his angel and rescued me7 from Herod's clutches and from everything the Jewish people were anticipating."
References for Acts 12:11