After a number of group attacks, an individual comes to Jesus. This scribe wants to ask which law in all 613 of the Old Testament commandments comes first and provides the core principle that unites all the others. Jesus’ answer points him to trust in God alone as the unifying principle. This is to be expressed in an all-encompassing love for God and when truly practised it frees one to love other people sacrificially. Jesus is pointing to the laws of Moses in saying this, but he’s describing the life his kingdom must show with the help of the Holy Spirit.
Photo from Oxfordian Kissuth on Wikipedia
And here is a short talk based on the same passage: He Changed The World (Episode 52)