1 Corinthians 9:16-18

For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel! For if I do this thing willingly, I have a reward: but if against my will, a dispensation of the gospel is committed unto me. What is my reward then? Verily that, when I preach the gospel, I may make the gospel of Christ without charge, that I abuse not my power in the gospel.