2 Corinthians 13:11

Thus the apostle concludes this epistle with, I. A valediction. He gives them a parting farewell, and takes his leave of them for the present, with hearty good wishes for their spiritual welfare. In order to this, 1. He gives them several good exhortations. (1.) To be perfect, or to be knit together in love, which would tend greatly to their advantage as a church, or Christian society. (2.) To be of good comfort under all the sufferings and persecutions they might endure for the cause of Christ or any calamities and disappointments they might meet with in the world. (3.) To be of one mind, which would greatly tend to their comfort; for the more easy we are with our brethren the more ease we shall have in our own souls. The apostle would have them, as far as was possible, to be of the same opinion and judgment; however, if this could not be attained, yet, (4.) He exhorts them to live in peace, that difference in opinion should not cause an alienation of affections - that they should be at peace among themselves. He would have all the schisms that were among them healed, that there should be no more contention and wrath found among them, to prevent which they should avoid debates, envyings, backbitings, whisperings, and such like enemies to peace. 2. He encourages them with the promise of God's presence among them: The God of love and peace shall be with you, Co2 13:11.

— Matthew Henry's Concise Commentary (public domain)

farewell--meaning in Greek also "rejoice"; thus in bidding farewell he returns to the point with which he set out, "we are helpers of your joy" (Co2 1:24; Phi 4:4). Be perfect--Become perfect by filling up what is lacking in your Christian character (Eph 4:13). be of good comfort-- (Co2 1:6; Co2 7:8-13; Th1 4:18).

— Jamieson-Fausset-Brown Commentary (public domain)