John Chrysostom

"He that glorieth, let him glory in the Lord." This also, he saith, accrueth to us from God.

Homily 22 on 2 Corinthians ↗

Theophylact of Ohrid

For, in performing such deeds, we do not boast nor ascribe anything in them to ourselves, but all of this, and the very measure to which we have attained, we attribute to God. This is what they too should boast about.

Commentary on 2 Corinthians ↗

Ignatius of Antioch

Keep thyself pure as the habitation of God. Thou art the temple of Christ. Thou art the instrument of the Spirit. Thou knowest in what way I have brought thee up. Though I am the least of men, do thou seek to follow me, be thou an imitator of my conduct. I do not glory in the world, but in the Lord. I exhort Hero, my son; "but let him that glorieth, glory in the Lord." May I have joy of thee, my dear son, whose guardian may He be who is the only unbegotten God, and the Lord Jesus Christ! …

Epistle of Pseudo-Ignatius to Hero, a Deacon of Antioch ↗

Thomas Aquinas

Then when he says, Let him who boasts, boast of the Lord, he shows that he is not going beyond the measure as to that in which he glories, saying: if I glory in him in whom one should glory, I am not going beyond. But since one should glory in God, Let him who boasts, boast of the Lord: "Let him who glories glory in this, that he understands and knows me" (Jer. 9:24). This can be explained in three ways: in one way, Let him who boasts, boast of the Lord, so that in the Lord denotes the object in which he glories. …

Commentary on 2 Corinthians ↗