Matthew 22:40

Or, because he that has fulfilled the things that are written concerning the love of God and our neighbour, is worthy to receive from God the great reward, that he should be enabled to understand the Law and the Prophets.

But His commandments, and the sum of them, are, "Thou shalt love the Lord thy God, and thy neighbor as thyself." If therefore to love God is to love one's neighbor, "For if thou lovest me," He saith, "O Peter, feed my sheep," but to love one's neighbor worketh a keeping of the commandments, with reason doth He say, "On these hang all the law and the prophets." So therefore what He did before, this He doth here also. I mean, that both there, when asked about the manner of the resurrection, He also taught a resurrection, instructing "For charity envieth not." By this He shows Himself to be submissive both to the law and to the prophets.

(Quaest. Ev. i. 33.) Hang, that is, refer thither as their end.

(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.

For to these two commandments belongs the whole decalogue; the commandments of the first table to the love of God, those of the second to the love of our neighbour.