The apostle had no wordly design in his preaching. Suffering in a good cause should sharpen holy resolution. The gospel of Christ at first met with much opposition; and it was preached with contention, with striving in preaching, and against opposition. And as the matter of the apostle's exhortation was true and pure, the manner of his speaking was without guile. The gospel of Christ is designed for mortifying corrupt affections, and that men may be brought under the power of faith. This is the great motive to sincerity, to consider that God not only sees all we do, but knows our thoughts afar off, and searches the heart. And it is from this God who trieth our hearts, that we must receive our reward. The evidences of the apostle's sincerity were, that he avoided flattery and covetousness. He avoided ambition and vain-glory.