Wherefore shew ye to them. — In adding “before the churches” (literally, in the face of the churches), St. Paul appeals, as he has done throughout the chapter, to that natural love of praise which takes its place as a legitimate, though it may be, and ought to be, a subordinate, motive for the activity of Christian benevolence. They were not to consider only what he and Titus and the two brethren would think of them. The eyes of the churches were upon them. Probably Philippi, Thessalonica, and Berœa are referred to.
The proof of your love, and of our boasting. — The “love” to which he appeals is probably their personal regard for him. What the “boast” was he states more fully in 2 Corinthians 9:2. With a subtle knowledge of human nature, he attacks them, as it were, on every side. They have to compete with Macedonia; they have to show their love for their teacher; they have to sustain their own reputation.