Adam Clarke on Acts 26:27

Believest thou the prophets? - Having made his elegant compliment and vindication to Festus, he turns to Agrippa; and, with this strong appeal to his religious feeling, says, Believest thou the prophets? and immediately anticipates his reply, and, with great address, speaks for him, I know that thou believest. The inference from this belief necessarily was: "As thou believest the prophets, and I have proved that the prophets have spoken about Christ, as suffering and, triumphing over death, and that all they say of the Messiah has been fulfilled in Jesus of Nazareth, then thou must acknowledge that my doctrine is true."