Acts 12:9

American Standard Version

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

Acts 12:9 in other translations

And he went out and followed him. He didn’t know that what was being done by the angel was real, but thought he saw a vision.

7And behold, an angel of the Lord stood by him, and a light shined in the cell: and he smote Peter on the side, and awoke him, saying, Rise up quickly. And his chains fell off from his hands.
8And the angel said unto him, Gird thyself, and bind on thy sandals. And he did so. And he saith unto him, Cast thy garment about thee, and follow me.
9And he went out, and followed; and he knew not that it was true which was done by the angel, but thought he saw a vision.
10And when they were past the first and the second guard, they came unto the iron gate that leadeth into the city; which opened to them of its own accord: and they went out, and passed on through one street; and straightway the angel departed from him.
11And when Peter was come to himself, he said, Now I know of a truth, that the Lord hath sent forth his angel and delivered me out of the hand of Herod, and from all the expectation of the people of the Jews.