Adam Clarke on Acts 17:31

He hath appointed a day - He has fixed the time in which he will judge the world, though he has not revealed this time to man.

By that man whom he hath ordained - He has also appointed the judge, by whom the inhabitants of the earth are to be tried.

Whereof he hath given assurance - ΠιϚιν παρασχων πασιν, Having given to all this indubitable proof, that Jesus Christ shall judge the world, by raising him from the dead. The sense of the argument is this: "Jesus Christ, whom we preach as the Savior of men, has repeatedly told his followers that he would judge the world; and has described to us, at large, the whole of the proceedings of that awful time, Mat 25:31, etc.; Joh 5:25. Though he was put to death by the Jews, and thus he became a victim for sin, yet God raised him from the dead. By raising him from the dead, God has set his seal to the doctrines he has taught: one of these doctrines is, that he shall judge the world; his resurrection, established by the most incontrovertible evidence, is therefore a proof, an incontestable proof, that he shall judge the world, according to his own declaration."