John Chrysostom

Now we have a natural law implanted in us, by which we distinguish between what is virtue, and what is vice. Hence it follows, And as ye would that men should do unto you, do ye also to them. He does not say, Whatever ye would not that men should do unto you, do not ye. For since there are two ways which lead to virtue, namely, abstaining from evil, and doing good, he names one, signifying by it the other also. …

Catena Aurea by Aquinas ↗

Clement of Alexandria

Here is then a comprehensive precept, and an exhortation of life, all-embracing: "As ye would that men should do unto you, do ye likewise to, them." We may comprehend the commandments in two, as the Lord says, "Thou shalt love the Lord thy God with all thy heart, with all thy soul, and with all thy strength; and thy neighbour as thyself." Then from these He infers, "on this hang the law and the prophets."

The Instructor Book 3 ↗

Desert Fathers

Some of the hermits used to say, 'Whatever you hate for yourself, do not do it to someone else. If you hate being spoken evil of, do not speak evil of another. If you hate being slandered, do not slander another. If you hate him who tries to make you despised, or wrongs you, or takes away what is yours, or anything like that, do not do such things to others. To keep this is enough for salvation.'

The Desert Fathers, Sayings of the Early Christian Monks ↗

Bede

And as you would that men should do to you, do also to them likewise. Because charity is patient, kind, it not only bravely endures the injuries of an enemy but also most graciously anticipates the kindness of a friend. For reciprocating the love of a lover, nature taught all. But to compel someone who does not love to love through benefits, only the perfect doctrine of Christ has taught. When He commanded us first to do to others as we would have done to us, He immediately confirmed the same notion more broadly, saying:

On the Gospel of Luke ↗

Bonaventure

For the perfection of benevolence it is also required that a person do good in all things: whence it is added: And as you wish that people would do to you, do also to them likewise. And note that he does not say: as they do, but: as you wish, because everyone wishes, when he is in need, to have good done to him and to be relieved in every necessity: Proverbs twenty-four: "Do not say: As he has done to me, so will I do to him, and I will render to each one according to his work." In this commandment is the fulfillment of the natural …

Commentary on Luke, Chapter 6 ↗