From everyday life (1 Corinthians 9:6–7), the Law of Moses (1 Corinthians 9:8–10), the temple service (1 Corinthians 9:13), and Christ’s own commands (verse 1 Corinthians 9:14), Paul has clearly demonstrated that it is his and Barnabas’ right to have their material needs provided for.
This makes Paul’s defence all the more compelling. That he has preached the gospel (and is determined to continue doing so) without receiving material support is a mark of his selfless service to the gospel. It is his ground for boasting.
Paul’s boasting is not like the worldly, arrogant boasting of the Corinthians (1 Corinthians 5:2, 1 Corinthians 5:6). Later, he will write that he boasts only in his weakness (2 Corinthians 11:30), since his weakness serves to display God’s power (2 Corinthians 12:9). This is certainly true of Paul’s work as a manual labourer. While this work has made him weak in the eyes of the world, it has enabled him to glorify Christ all the more (see 1 Corinthians 9:12).
15 Pour moi, je n'ai usé d'aucun de ces droits, et ce n'est pas afin de les réclamer en ma faveur que j'écris ainsi; car j'aimerais mieux mourir que de me laisser enlever ce sujet de gloire.