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; and yet there were those among them who upon these heads created him great uneasiness. Note, It is no strange nor new thing for a minister to meet with very unkind returns for great good-will to a people, and diligent and successful services among them. Some among the Corinthians questioned, if they did not disown, his apostolical character. To their cavils he here answers, and in such a manner as to set forth himself as a remarkable example of that self-denial, for the good of others, which he had been recommending in the former chapter. And, 1. He asserts his apostolical mission and character: Am I not an apostle? Have I not seen Jesus Christ our Lord? To be a witness of his resurrection was one great branch of the apostolical charge. "Now," says Paul, "have not I seen the Lord, though not immediately after his resurrection, yet since his ascent?" See Co1 4:8. "Am I not free? Have I not the same commission, and charge, and powers, with the other apostles? What respect, or honour, or subsistence, can they challenge, which I am not at liberty to demand as well as they?" It was not because he had no right to live of the gospel that he maintained himself with his own hands, but for other reasons. 2. He offers the success of his ministry among them, and the good he had done to them, as a proof of his apostleship: "Are not you my work in the Lord? Through the blessing of Christ on my labours, have not I raised a church among you? The seal of my apostleship are you in the Lord. Your conversion by my means is a confirmation from God of my mission." Note, The ministers of Christ should not think it strange to be put upon the proof of their ministry by some who have had experimental evidence of the power of it and the presence of God with it. 3. He justly upbraids the Corinthians with their disrespect: "Doubtless, if I am not an apostle to others, I am so to you, Co1 9:2. I have laboured so long, and with so much success, among you, that you, above all others, should own and honour my character, and not call it in question." Note, It is no new thing for faithful ministers to meet with the worst treatment where they might expect the best. This church at Corinth had as much reason to believe, and as little reason to question, his apostolical mission, as any; they had as much reason, perhaps more than any church, to pay him respect. He had been instrumental in bringing them to the knowledge and faith of Christ; he laboured long among them, nearly two years, and he laboured to good purpose, God having much people among them. See Act 18:10, Act 18:11. It was aggravated ingratitude for this people to call in question his authority.

If I be not an apostle unto others - If there be other Churches which have been founded by other apostles; yet it is not so with you.

The seal of mine apostleship are ye - Your conversion to Christianity is God's seal to my apostleship. Had not God sent me, I could not have profited your souls.

The σφραγις or seal, was a figure cut in a stone, and that set in a ring, by which letters of credence and authority were stamped. The ancients, particularly the Greeks, excelled in this kind of engraving. The cabinets of the curious give ample proof of this; and the moderns contend in vain to rival the perfection of those ancient masters.

In the Lord - The apostle shows that it was by the grace and influence of God alone that he was an apostle, and that they were converted to Christianity.

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 I am to you; all the signs of apostleship were wrought among them; not only the grace of God was implanted in them under his ministry, but the extraordinary gifts of the Spirit were received by them through it; and many signs, wonders, and mighty deeds, were done in the midst of them by him: see Co2 12:12 which were sufficient to put the matter quite out of doubt with them:

for the seal of mine apostleship, are ye in the Lord; alluding to the sealing of deeds and writings, which render them authentic; or to the sealing of letters, confirming the truth of what is therein expressed; and the sense is, that their being converted persons, and so openly in the Lord, in union with him; or being made new creatures by the power of his grace, through his preaching, was an authentic proof of his apostleship, and served him instead of a letter testimonial and recommendatory; see Co2 3:1. Some copies read, "the seal of my epistle", and so the Ethiopic version.

yet doubtless--yet at least I am such to you.

seal of mine apostleship--Your conversion by my preaching, accompanied with miracles ("the signs of an apostle," Rom 15:18-19; Co2 12:12), and your gifts conferred by me (Co1 1:7), vouch for the reality of my apostleship, just as a seal set to a document attests its genuineness (Joh 3:33; Rom 4:11).