1 Corinthians 9:18
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.
Note 5 at 1Co 9:18: This does not mean that Paul didn't receive offerings. He instructed these Corinthian believers about collections for the poor saints in Jerusalem in this very letter (1Co 16:1-3). In his second letter to the Corinthians, he wrote two chapters about giving. However, Paul refused to have his personal needs met by the offerings given by the Corinthians (see note 5 at 1Co 9:6).