Charles Ellicott Commentary 1 Corinthians 9:20

"And to the Jews I became as a Jew, that I might gain Jews; to them that are under the law, as under the law, not being myself under the law, that I might gain them that are under the law;" — 1 Corinthians 9:20 (ASV)

And unto the Jews I became as a Jew.—This and the following verses are a categorical explanation of the previous statements. They show in detail both how he became the slave of all and the reward he had in view in doing so.

For example, of St. Paul’s conformity to Jewish law, see Acts 16:3; Acts 18:18; Acts 20:6; Acts 21:26.

To them that are under the law. . . .—Better, To them that are under the Law, as under the Law, not being myself under the Law. These last words are found in all the best manuscripts, but have been omitted by an oversight of the copyist in the text used for the English translation of that era. Those spoken of as “Jews” are, of course, Jews by birth and religion; those “under the Law” are probably proselytes to Judaism. In neither case do they mean Christian converts, for the object of St. Paul’s conduct towards those of whom he here speaks was to win them to the Faith of Christ. He himself was no longer “under the Law,” being a Christian (Galatians 2:19).