From Mark 12:28-32
And one of the scribes came up and heard them disputing with one another, and seeing
that he answered them well, asked him, "Which commandment is the first of all?"
Jesus answered, "The first is, 'Hear, O Israel: the Lord our God, the Lord is one;
and you shall love the Lord your God with all your heart, and with all your soul,
and 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."
And the scribe said to him, "You are right, Teacher; you have truly said that he is one, and
there is no other but he."