This coming Sunday is the 31st Sunday in Year B. Our gospel is taken from the Gospel of Mark in which Jesus is asked which of the commandments is the first and greatest. Jesus has responded: 29 …“The first is this: ‘Hear, O Israel! The Lord our God is Lord alone! 30 You shall love the Lord your God with all your heart, with all your soul, with all your mind, and with all your strength. The second is this: ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.
In the first words of the Shemaʿ (“our Lord our God is Lord alone”) we discover the root of the command to love God. God is the only God (Lord alone) and uniquely in a covenant bond with Israel (our God). Because of the gracious favor in extending his covenant love to Israel, the Lord our God is to be loved with a completeness of devotion which is defined by the repeated “all” – heart, soul, mind, strength. Because the whole person is the focus of God’s covenant love, the whole person is claimed by God for Himself. To love God in the way defined by the great commandment is to seek God for his own sake, to have pleasure in him and to strive after him.
“There is no other commandment greater than these.” There was always an ongoing debate among Sadducees, Pharisees and Scribes about distinctions between lighter and weightier, smaller and greater commandments. The question to Jesus was just an inevitable feature of Palestinian piety, since it was traditional to speak of the 613 individual statutes of the Law. The basis of distinguishing between small and great commandments was generally the nature of the demand (in the case of commandments) or of the sacrificial offering/compensation demanded.
William Lane  offers: “Jesus’ response goes much deeper than the distinction between small and great commandments and shows that he understood the question to concern the principle of Law. The attempt to summarize the whole Law in a single utterance was remembered in anecdotes concerning some of the early scribal teachers. When challenged by a Gentile, Hillel the Elder (ca. 40 B.C.-A.D. 10) replied: ‘What you yourself hate, do not do to your neighbor: this is the whole Law, the rest is commentary. Go and learn it.’ For Jesus the whole Law is summarized in the will of God which calls for the love which is a whole-hearted response to God and to the neighbor.”
William L. Lane, The Gospel of Mark in The New International Commentary on the New Testament (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1974) p.432