Albert Barnes on Acts 12:11

And when Peter was come to himself. This expression naturally means, when he had overcome his amazement and astonishment at the unexpected deliverance, so as to be capable of reflection. He had been amazed by the whole transaction. He thought it was a vision; and in the suddenness and rapidity with which it was done, he had no time for cool reflection. The events of Divine Providence often overwhelm and amaze us; and such are their suddenness, and rapidity, and unexpected character in their development, as to confound us, and prevent calm and collected reflection.

Of a surety. Certainly; surely. He considered all the circumstances; he saw that he was actually at liberty and that it could have been effected only by Divine interposition.

The expectation of the people. From this it appears that the people earnestly desired his death; and it was to gratify that desire that Herod had imprisoned him.

(**) "surety" "Certainty" (e) "his angel" 2Chr 16:9, Ps 34:7, Dan 3:28, 6:22, Heb 1:14 (f) "hath delivered" Ps 33:18,19, 97:10, 2Cor 1:10, 2Pet 2:9