Adam Clarke on Acts 8:13

Simon himself believed also - He was struck with the doctrine and miracles of Philip - he saw that these were real; he knew his own to be fictitious. He believed therefore that Jesus was the Messiah, and was in consequence baptized.

Continued with Philip, and wondered - ΕξιϚατο, He was as much astonished and confounded at the miracles of Philip as the people of Samaria were at his legerdemain. It is worthy of remark that εξιϚατο comes from the same root, εξιϚημι, as the word εξιϚων, in Act 8:9, and, if our translation bewitched be proper there, it should be retained here; and then we should read, Then Simon himself believed and was baptized, and continued with Philip, being Bewitched, beholding the miracles and signs which were done. We may see, from this circumstance, how improper the term bewitched is, in the 9th and 11th verses.