“And the second is like, namely this, Thou shalt love thy neighbour as thyself. There is none other commandment greater than these.”
Mark 12:31 — Greek Interlinear
Church Fathers on Mark 12:31
This question is only that which is a problem common to all skilled in the law, namely, that the commandments are differently set forth in Exodus, Leviticus, and Deuteronomy. Wherefore He brought forward not one but two commandments, by which, as by two paps rising on the breast of the bride, our infancy is nourished.
See how He has enumerated all the powers of the soul; for there is a living power in the soul, which He explains, when He says, 'With all thy soul,' and to this belong anger and desire, all of which He will have us give to Divine love.
He shews when he says, 'this is greater than all sacrifices,' that a grave question was often debated between the scribes and Pharisees, which was the first commandment, or the greatest of the Divine law; that is, some praised offerings and sacrifices, others preferred acts of faith and love, because many of the fathers before the law pleased God by that faith only, which works by love. This scribe shews that he was of the latter opinion.