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.
Note 1 at Ac 12:6: Peter was well aware that Herod planned to kill him--as he had James (Ac 12:2)--the next morning. Peter also knew that Jesus had told him he would be martyred (Joh 21:18-19). In the natural, this looked like the end for Peter. Yet Peter was not wringing his hands, pacing the floor, or even praying. He was fast asleep.
This is a tremendous statement about Peter's faith in the Lord. Before, Peter had bitterly denied the Lord because he was afraid of persecution (Mt 26:69-75, Mr 14:66-72, Lu 22:55-62, and Joh 18:15-27), but he had resolved to such a degree that it would never happen again that there was no agonizing over it now. We need to have already settled in our hearts what we will do in crisis situations before the crises come.
Note 2 at Ac 12:6: As mentioned in note 2 at Ac 12:4, Peter had sixteen soldiers assigned to him, four on each watch. The way that this verse describes the soldiers guarding him, it appears that two of the soldiers were chained to him, one on each side, and two soldiers were outside the cell, guarding the door. Having the two soldiers chained to Peter was different than the way the apostles had been imprisoned before (Ac 5:23) and could reflect Herod's knowledge of their previous escape and his determination not to let that happen again (see note 3 at Ac 12:4).