Acts 12:9

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 .

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.

And he went out, and followed him; and wist not that it was true which was done by the angel; but thought he saw a vision.