Charles Spurgeon Commentary Acts 25:20-22

"And I, being perplexed how to inquire concerning these things, asked whether he would go to Jerusalem and there be judged of these matters. But when Paul had appealed to be kept for the decision of the emperor, I commanded him to be kept till I should send him to Caesar. And Agrippa [said] unto Festus, I also could wish to hear the man myself. To-morrow, saith he, thou shalt hear him." — Acts 25:20-22 (ASV)

So Paul's witness-bearing was made to spread still further. It is scarcely possible to conceive of any other circumstances in which the gospel could have been made known to such an audience as the apostle was, the next day, to have the opportunity to address.