Moreover, the Lord Jesus Himself teaches us that the whole law and the prophets hang upon the two precepts of love to God and love to our neighbour. Concerning these two commandments the following is written in the Gospel according to St. Mark: “And one of the scribes came, and having heard them reasoning together, and perceiving that He had answered them well, asked Him: Which is the first commandment of all? And Jesus answered him: The first of all the commandments is, Hear, O Israel! the Lord our God is one Lord; and thou shalt love the Lord thy God with all thine heart, and with all thy soul, and with all thy mind, and with all thy strength. This is the first commandment. And the second is like unto it: Thou shalt love thy neighbour as thyself. There is none other commandment greater than these.” Also, in the Gospel according to St. John, He says, “A new commandment I give unto you, that ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples, if ye have love to one another.”
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 1, vol. 5 (Schaff, 1887), public domain (Public domain).