New Defender's Study Bible Notes
12:6 Peter was sleeping. In spite of his miserable circumstances and the probability of being executed the next morning, Peter was sleeping so soundly that the angel had to strike him and lift him up. Even then, Peter still thought he was dreaming until the angel left him outside in the street (Acts 12:10). Peter surely experienced the reality of Psalm 121:3, assuring him that “He that keepeth thee will not slumber,” and of Psalm 127:2, which says, “He giveth His beloved sleep.”
12:7 angel of the Lord. Peter had experienced a similar angelic release from prison at least once before (Acts 5:19), so he knew that God was still in control.
12:9 wist. That is, “know.”