1 Corinthians 9:17-19
Revised Standard Version
17 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. 18 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.
19 For though I am free from all men, I have made myself a slave to all, that I might win the more.Read full chapter