Adam Clarke on 2 Corinthians 10:7

Do ye look on things after the outward appearance? - Do not be carried away with appearances; do not be satisfied with show and parade.

If any man trust to himself that he is Christ's - Here, as in several other places of this and the preceding epistle, the τις, any or certain, person, most evidently refers to the false apostle who made so much disturbance in the Church. And this man trusted to himself - assumed to himself that he was Christ's messenger: it would not do to attempt to subvert Christianity at once; it had got too strong a hold of Corinth to be easily dislodged; he therefore pretended to be on Christ's side, and to derive his authority from him.

Let him of himself - Without any authority, certainly, from God; but, as he arrogates to himself the character of a minister of Christ, let him acknowledge that even so we are Christ's ministers; and that I have, by my preaching, and the miracles which I have wrought, given the fullest proof that I am especially commissioned by him.