1 Corinthians 9:17-21

For if I do this voluntarily, I have a reward; but if against my will, I have been entrusted with a commission nonetheless.

What, then, is my reward? That, when I preach the gospel, I may offer the gospel without charge, so as not to make full use of my right in the gospel.

For though I am free from all people, I have made myself a slave to all, so that I may gain more.

To the Jews I became as a Jew, so that I might gain Jews; to those who are under the Law, I became as one under the Law, though not being under the Law myself, so that I might gain those who are under the Law;

to those who are without the Law, I became as one without the Law, though not being without the law of God but under the law of Christ, so that I might gain those who are without the Law.