'Am I not free? Am I not an apostle? Have I not seen Jesus our Lord? Are you not my work in the Lord? If to others I am not an apostle, yet at least I am to you, for the seal of my apostleship are you in the Lord.'
He begins by asserting his freedom. Support is something he has a right to and he would therefore be free to receive it if he wished. And the reason he has that right is because he is an Apostle, one sent forth and therefore dependent on such support (Matthew 10:9-15). But because he is wholly free he can choose what he will do, and he has the right to do either.
His evidence that he is an Apostle rests first on that he has seen 'Jesus our Lord'. He has seen Jesus, the One Who walked on earth as man, the resurrected Jesus, as now raised to Lordship. And the second that his Apostleship has been revealed by his success in establishing this new church. They are his work in the Lord. If they enjoy spiritual gifts let them remember who first brought the Spirit among them. They are the evidence, indeed the seal of his Apostleship. They are proof of his Apostolic power and authority, and therefore of his rights.