Romans 15:5

The apostle, having delivered two exhortations, before he proceeds to more, intermixes here a prayer for the success of what he had said. Faithful ministers water their preaching with their prayers, because, whoever sows the seed, it is God that gives the increase. We can but speak to the ear; it is God's prerogative to speak to the heart. Observe, I. The title he gives to God: The God of patience and consolation, who is both the author and the foundation of all the patience and consolation of the saints, from whom it springs and on whom it is built. He gives the grace of patience; he confirms and keeps it up as the God of consolation; for the comforts of the Holy Ghost help to support believers, and to bear them up with courage and cheerfulness under all their afflictions. When he comes to beg the pouring out of the spirit of love and unity he addresses himself to God as the God of patience and consolation; that is, 1. As a God that bears with us and comforts us, is not extreme to mark what we do amiss, but is ready to comfort those that are cast down - to teach us so to testify our love to our brethren, and by these means to preserve and maintain unity, by being patient one with another and comfortable one to another. Or, 2. As a God that gives us patience and comfort.

— Matthew Henry's Concise Commentary (public domain)

Now the God of patience and consolation--Such beautiful names of God are taken from the graces which He inspires: as "the God of hope" (Rom 15:13), "the God of peace" (Rom 15:33). grant you to be likeminded--"of the same mind" according to Christ Jesus--It is not mere unanimity which the apostle seeks for them; for unanimity in evil is to be deprecated. But it is "according to Christ Jesus"--after the sublimest model of Him whose all-absorbing desire was to do, "not His own will, but the will of Him that sent Him" (Joh 6:38).

— Jamieson-Fausset-Brown Commentary (public domain)