Adam Clarke on Acts 28:23

To whom he expounded - the kingdom of God - To whom he showed that the reign of the Messiah was to be a spiritual reign; and that Jesus, whom the Jewish rulers had lately crucified, was the true Messiah, who should rule in this spiritual kingdom. These two points were probably those on which he expatiated from morning to evening, proving both out of the law and out of the prophets. How easily Jesus, as the Messiah, and his spiritual kingdom, might be proved from the law of Moses, any person may be satisfied, by consulting the notes written on those books. As to the prophets, their predictions are so clear, and their prophecies so obviously fulfilled in the person, preaching, miracles, passion, and death of Jesus Christ, that it is utterly impossible, with any show of reason, to apply them to any other.