After arresting him, he put him in prison, handing him over to be guarded by four squads of four soldiers each. Herod intended to bring him out for public trial after the Passover.1
So Peter was kept in prison, but the church was earnestly praying to God for him.2
The night before Herod was to bring him to trial, Peter was sleeping between two soldiers, bound with two chains,3 and sentries stood guard at the entrance.
Suddenly an angel4 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.5
Scripture quoted by permission. Quotations designated (NIV) are from THE HOLY BIBLE: NEW INTERNATIONAL VERSION®. NIV®. Copyright © 1973, 1978, 1984 by Biblica. All rights reserved worldwide.
(New International Version Bible Online)