'Preach the Gospel' in the Bible

For the Messiah did not send me to baptize but to preach the gospel, not with eloquent wisdom, so the cross of the Messiah won't be emptied of its power.

For if I preach the gospel, I have nothing to boast about, for this obligation has been entrusted to me. How terrible it would be for me if I didn't preach the gospel!

What, then, is my reward? It is to be able to preach the gospel free of charge, and so I never resort to demanding my rights when I'm preaching the gospel.

Then we can preach the gospel in the regions far beyond you without boasting about things already accomplished by someone else.