William Burkitt on Ephesians 3:1

For this cause, that is, for preaching the gospel to the Gentiles in general; and in particular, for asserting, that the privileges of justification and salvation by Christ belonged equally to the Gentiles as well as the Jews, though they were not circumcised; for this cause I was persecuted and imprisoned by the Jews.

Where observe, The apostle styles himself Christ's prisoner; I Paul, the prisoner of Jesus Christ. He was at once Christ's prisoner, the Jews' prisoner, the Romans' prisoner, the Gentiles' prisoner; Christ's prisoner, as suffering for his gospel; the Jews' prisoner, as suffering by their accusation; the Romans' prisoner, as suffering by their sentence; the Gentiles prisoner, as suffering for his labours in order to their salvation.

Lord! what a title of honour is here put upon the apostle! I Paul, the prisoner of Jesus Christ. His imprisonment for Christ was verily a greater honour, and matter of higher glorying, than his rapture into the third heavens.