Matthew 22:34-40

Now when the Pharisees heard that He had silenced (muzzled) the Sadducees, they gathered together. And one of their number, a lawyer, asked Him a question to test Him. Teacher, which kind of commandment is great and important (the principal kind) in the Law? [Some commandments are light–which are heavy?] And He replied to him, You shall love the Lord your God with all your heart and with all your soul and with all your mind (intellect). [Deut. 6:5.] This is the great (most important, principal) and first commandment. And a second is like it: You shall love your neighbor as [you do] yourself. [Lev. 19:18.] These two commandments sum up and upon them depend all the Law and the Prophets.