1 Corinthians 9:16-27
For if I preach the gospel, that gives me no ground for boasting. For necessity is laid upon me. Woe to me if I do not preach the gospel! For if I do this of my own will, I have a reward; but if not of my own will, I am entrusted with a commission. What then is my reward? Just this: that in my preaching I may make the gospel free of charge, not making full use of my right in the gospel. For though I am free from all men, I have made myself a slave to all, that I might win the more.
To the Jews I became as a Jew, in order to win Jews; to those under the law I became as one under the law--though not being myself under the law--that I might win those under the law. To those outside the law I became as one outside the law--not being without law toward God but under the law of Christ--that I might win those outside the law. To the weak I became weak, that I might win the weak. I have become all things to all men, that I might by all means save some. I do it all for the sake of the gospel, that I may share in its blessings. Do you not know that in a race all the runners compete, but only one receives the prize? So run that you may obtain it. Every athlete exercises self-control in all things. They do it to receive a perishable wreath, but we an imperishable. Well, I do not run aimlessly, I do not box as one beating the air; but I pommel my body and subdue it, lest after preaching to others I myself should be disqualified.