The Apostle Paul
1 Corinthians 9:2ESV·traditional attribution

If to others I am not an apostle, at least I am to you, for you are the seal of my apostleship in the Lord.

John Calvin Reformed @genevareformer

2. If I am not an Apostle to others The sum of this tends to the establishing of his authority among the Corinthians, so as to place it beyond all dispute. “If there are those,” says he, “who have doubts as to my Apostleship, to you, at least, it ought to be beyond all doubt, for, as I planted your Church by my ministry, you...

Matthew Henry Presbyterian @wholebiblehenry

Blessed Paul, in the work of his ministry, not only met with opposition from those without, but discouragement from those within. He was under reproach; false brethren questioned his apostleship, and were very industrious to lessen his character and sink his reputation; particularly here at Corinth, a place to which he had been instrumental in doing much good, and from which he had deserved well...

Commenting on 1 Corinthians 9:1-2

John Gill Reformed Baptist @doctorgill

If I be not an apostle unto others,.... This is said by way of supposition, not concession; for he was an apostle to many others; he was an apostle of the Gentiles in general; as the apostleship of the circumcision belonged to Peter, that of the uncircumcision fell to his share: but however, as if he should say, be that as it will, yet doubtless...