John Calvin on Acts 25:14-17

14. When many days. Therefore, when (after some time was spent) they wanted matter of talk, as idle men use to invent somewhat whereon they may talk, mention was made of Paul; for Luke meant to note that, when he said that after many days were idly spent, Festus told the king of a certain man which lay bound. And although he doth here both touch the malice of the priests, and also make a show of wonderful equity on his part, yet in that he shortly after cleareth the party which was accused, he condemneth himself unawares, when as he confesseth that he was enforced to appeal that he might not be carried to Jerusalem.

But when Festus commendeth the Romans, he showeth what doth beseem judges. And if nature did tell profane men thus much, that they must admit no such favor as may oppress the guiltless, how much more must judges (who have the light of the word of God) be careful to avoid all corruption.