Acts 25:13-22. Paul is still in the custody of Governor Festus in Caesarea when the Jewish king Herod Agrippa and Bernice* pay Festus a visit to welcome him as governor. Festus discusses Paul with them, saying that the Jews' case against Paul seems to be a "dispute with him about their own superstition and about one Jesus, who was dead, but whom Paul asserted to be alive." Festus says he is at a loss as to how to investigate these matters and that Paul has asked to be sent to Caesar, which he is planning to do. Agrippa says he would like to hear Paul himself, and Festus promises that he shall do so the next day.

Herod Agrippa it is not the Herod who heard Jesus' case and sent him back to Pilate, but his successor. The story of Paul is now very similar to that of Jesus, though - the Jews are upset with Paul and want to kill him; the Romans are confused as to what he's done wrong, but do not want to antagonize the Jews; and now we have another Herod the scene, too!

One difference in the two cases, though, is that Paul always defends himself while Jesus remained silent in the face of false accusations. By speaking up, Paul is spreading the Word even more - he is speaking only of Christ, not of himself, and every time he has to defend himself is another opportunity to talk about Christ. Jesus, on the other hand, knew that He had to die for our salvation. He could have defended Himself easily, He even says His Father would send legions of angels if He but asked, but if He had defended himself, He would not have been crucified, and we would not be saved. Because Jesus did accomplish His mission, He gained our salvation, and the Church, of which Paul is one of the most important first members, was born. So Paul's mission is to speak about Christ, and Him crucified, at every opportunity, even when he is defending himself from false accusations. It is of the utmost importance for Paul to do so, and he takes every opportuntiy to do it.

Jesus remained silent because silence accomplished His mission, and because there was really nothing other than dying and rising that would prove He was who He said He was.  Paul, on the other hand, has to spread the word that Christ did die and has risen. That is the Good News, the message that all the world needs to hear, and Paul talks about it at every opportunity, as he must. 

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* Bernice was Agrippa's sister with whom he was involved in an incestuous relationship. See https://www.bibleversestudy.com/acts/acts25-king-agrippa-and-bernice.htm.