Matthew 22:34-40, Mark 12:28-31.
An expert in the law, tested Jesus asking what is the greatest commandment in the Law. Jesus replied: "'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment. And the second is like it: 'Love your neighbor as yourself.' All the Law and the Prophets hang on these two commandments."
Jesus quoted these from Deuteronomy 6:5 and Leviticus 19:18.
