Matthew 22:34-40:

When the Pharisees heard that Jesus had left the Sadducees speechless, they gathered together, and one of them, an expert on the Law, attempted to trick Jesus with this question: “Teacher, which commandment of the Law is the greatest?” Jesus answered: “You must love the Most High God with all your heart, with all your soul and with all your mind. That is the greatest and first commandment. The second is like it; You must love your neighbor as yourself. On these two commandments the whole Law is based– and the Prophets as well.”