34 But when the Pharisees heard that He had silenced the Sadducees, they gathered together.
35 Then one of them, a lawyer, asked Him a question, testing Him, and saying,
36 “Teacher, which is the great commandment in the law?”
37 Jesus said to him, “‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’
38 This is the first and great commandment.
39 And the second is like it: ‘You shall love your neighbor as yourself.’
40 On these two commandments hang all the Law and the Prophets.”
This account also appears in Mark 12:28-34.
lawyer (v.35) — an expert in Old Testament law
great commandment (v.36) — This does not mean, “Name one of the commandments which is greater than the rest.” The particular word translated “which” is qualitative; and therefore the meaning of the lawyer was, “What is the principle which makes any commandment great?” In that day men were teaching the relative importance of the commandments. There was a school of interpretation which taught that the third commandment in the Decalogue was the supreme commandment, and that all the rest were minor ones; and so this particular question grew out of the differences of opinion concerning which commandments were greatest, and they asked Christ to decide what was the real principle by which they might test the greatness of a commandment. — Morgan, pages 269-270.
In verses 37 and 39, Jesus referred to Deuteronomy 6:5 and Leviticus 19:18.
with all your heart (v.37) — In Hebrew thought, the total being (Deuteronomy 6:4-9; 11:13-21; Numbers 15:37-41).
The Pharisees had codified the law into 248 commandments and 365 prohibitions. These 613 precepts were imposed by the Pharisees on their followers as their obligation. When a Jew tried to fulfill the requirements of the law so codified, it sometimes appeared to that person as though one law came into conflict with another law. It was necessary then to determine which of the two took precedence so that if a law had to be violated because of the conflict, one would violate the lesser and not the more important law. There was constant argument among the Pharisees concerning which commandment took precedence over the other. The Pharisees had not been able to solve the problem or further reduce their codification of the law to assist their disciples in this observance. The Pharisees were testing Christ to see whether He had greater insight into the law than they had. Christ summarized the demands of the Mosaic law under two precepts. The first was an all-inclusive precept that governed their responsibility toward God, “Love the Lord your God with all your heart and with all your soul and with all your mind” (Matthew 22:37). The second precept was all-inclusive of their responsibility to man, “Love your neighbor as yourself” (v.30). — Pentecost, pages 390-391.