Master, which is the great commandment in the law?

People's New Testament

22:36 Which is the great commandment? This was a question which, with some others, divided the Jewish teachers into rival schools, and was a constant bone of contention--one of those strivings about the law, against which Paul warns Titus (Titus 3:9). The Jews divided their commandments into greater and lesser, but were not agreed in particulars. Some pronounced the law of circumcision the greater; others, that of sacrifices, or ablutions, or phylacteries. The Talmud reckoned the positive laws of Moses at 248, the negative at 365, in all 613. To keep so many laws, said the Jews, is an angel's work. So they had much question which was the great commandment, so that they might keep it in lieu of keeping the whole.

Matthew Henry's Concise Commentary

22:34-40 An interpreter of the law asked our Lord a question, to try, not so much his knowledge, as his judgment. The love of God is the first and great commandment, and the sum of all the commands of the first table. Our love of God must be sincere, not in word and tongue only. All our love is too little to bestow upon him, therefore all the powers of the soul must be engaged for him, and carried out toward him. To love our neighbour as ourselves, is the second great commandment. There is a self-love which is corrupt, and the root of the greatest sins, and it must be put off and mortified; but there is a self-love which is the rule of the greatest duty: we must have a due concern for the welfare of our own souls and bodies. And we must love our neighbour as truly and sincerely as we love ourselves; in many cases we must deny ourselves for the good of others. By these two commandments let our hearts be formed as by a mould.