Augustine of Hippo
Catena Aurea · Matthäusevangelium 22
But when the Pharisees had heard that he had put the Sadducees to silence, they were gathered together. Then one of them, which was a Lawyer, asked him a question, tempting him, and saying, Master, which is the great commandment in the Law? Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the Law and the Prophets. It follows, On these two commandments hang all the Law and the Prophets.
(de Trin. viii. 7.) Since there are two commandments, the love of God and the love of our neighbour, on which hang the Law and the Prophets, not without reason does Scripture put one for both; sometimes the love of God; as in that, We know that all tilings work together for good to them that love God; (Rom. 8:28.) and sometimes the love of our neighbour; as in that, All the law is fulfilled in one word,even in this, Thou shall love thy neighbour as thyself. (Gal. 5:14.) And that because if a man love his neighbour, it follows therefrom that he loves God also; for it is the selfsame affection by which we love God, and by which we love our neighbour, save that we love God for Himself, but ourselves and our neighbour for God’s sake.