Exhortation is a form of teaching. For teaching is generally called reasoning about any subject, while exhortation is properly when someone calms with a word souls disturbed by grief or anger. So, he says, let the exhorter remain in exhortation, doing his own work, and not exalt himself above another.
Rom. 12:8. Whether you distribute, distribute with simplicity; whether you lead, lead with diligence;
Having spoken about teaching and exhortation, that is, about what pertains to the care of souls, he now speaks about the bodily, as occupying second place. By "simplicity" he means generosity; consequently, he teaches to distribute with generosity. For no virtue is a virtue if it is performed in an improper manner. So too the virgins, although they had oil, did not have enough of it, which is why they were rejected. And a leader must carry out his service carefully and without laziness. "To lead" means to assist the one who needs help, by word and deed. Since he spoke about the distribution of possessions, and not all abound in possessions, he adds: be a leader in another way, and help those in need, only with diligence.
Rom. 12:8. he who gives, let him give with generosity.
He said above that one must give with simplicity or with generosity. But many give much, yet grudgingly and with sorrow, therefore he teaches that generosity must be without sorrow, even with pleasure and joy. You should rejoice that for a small price you receive heaven; understand, then, what the difference is between one who distributes and one who does good. The one who distributes gives alms from what he has received from another, while the one who does good gives from his own possessions.
Rom. 12:9. Love must be sincere;
He shows what brings to completion everything said before, and says: "let love be without hypocrisy." For such is true love, and with it everything will be easily accomplished: the benefactor will do good willingly, providing for his neighbor as for himself; the ruler will govern with diligence, striving for his neighbor as for himself, and so on.
Rom. 12:9. Abhor evil, cling to good;
Above he spoke of love. But since love can also be harmful, for example, among people who conspire together for robbery and the like, he adds: "abhor" (ἀποστυγούντες) evil, that is, hating evil from the soul; for the prefix (από) indicates a hatred that is strong and with the whole heart. There are not a few who, although they do not do evil, nevertheless desire it. Therefore, he says, I require that they hate evil with their whole heart, so that the soul may be purified. Since I, he says, have commanded you to love one another, do not think that I am urging you to assist one another in wicked deeds as well. Quite the contrary, I desire that you shun not only the wicked deed itself, but also every disposition of the soul toward it. It is not enough to turn away from evil; one must also devote oneself to doing good. Therefore he said: "cling to what is good," that is, have a disposition and love toward it. It is in this sense that God, joining husband and wife, said: "he shall cleave to his wife" (Gen. 2:24).
Rom. 12:10. Be tenderly affectionate one to another with brotherly love;
I, he says, have taught you love, and it is very natural for you to fulfill this, for you are brethren, born from one womb, that is, from the font of baptism; consequently, by this very fact you are already obliged to love one another, because the sign and manifestation of brotherhood is friendship, and friendship is produced and strengthened by brotherly love.
Rom. 12:10. In honor preferring one another;
He teaches how to preserve brotherly love, namely by respecting one another and mutual preference; for "to be kindly affectioned" means to anticipate one another in showing honor.
Rom. 12:11. Not slothful in zeal;
Since many, it would seem, honor and love one another in their souls, but do not extend their hands to them, he teaches us to care for one another and to help others by deed itself.
Rom. 12:11. Be fervent in spirit;
An objection is anticipated: how can we "not be slothful in zeal"? If, he answers, we are fervent in spirit, that is, if we are diligent and zealous. Note also that "be fervent in spirit" is said after the enumeration of many kinds of virtue; for whoever has fulfilled the above attracts the grace of the Spirit and is kindled by His fire.
Rom. 12:11. Serve the Lord;
When you are brotherly in love, when you have love and the other virtues spoken of before, then you are serving the Lord. For He regards as done to Himself what you do for your brother.
Rom. 12:12. Be comforted by hope;
Since what the Apostle demands is something great and difficult, he now teaches that which makes the fulfillment of this easy — he teaches action based on hope. For hope makes the soul more courageous and bold in dangers.
Rom. 12:12. In tribulation be patient,
Hope relates to the future. But, he says, even in the present you can receive a great good; for endurance in afflictions will make you patient and experienced.
Rom. 12:12. Constant in prayer;
This, I mean – prayer, is a great help toward the accomplishment of all the aforementioned. And he did not simply say: pray, but be "constant in prayer." If you do not receive anything immediately, be constant, and you will attain what you desire.