The Great Commandment (or Greatest Commandment) is a term used in the New Testament to describe the first of two commandments cited by Jesus in Matthew 22:35–40 and Mark 12:28–34. These two commandments are paraphrases taken from the Old Testament and are commonly seen as important to Jewish and Christian ethics.
In Mark, when asked "which is the great commandment in the law?", the Greek New Testament reports that Jesus answered, "Hear, O Israel! The Lord our God, The Lord is One; Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind", before also referring to a second commandment, "Thou shalt love thy neighbour as thyself." Most Christian denominations consider these two commandments the core of the Christian religion.
Then one of them, which was a lawyer, asked him a question, tempting him, and saying, Master, which is the great commandment in the law? Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets.
In the Gospel of Mark, the Shema is included:
And one of the scribes came, and having heard them reasoning together, and perceiving that he had answered them well, asked him, Which is the first commandment of all? And Jesus answered him, The first of all the commandments is, Hear, O Israel; The Lord our God is one Lord: And thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength: this is the first commandment. And the second is like, namely this, Thou shalt love thy neighbour as thyself. There is none other commandment greater than these.
And, behold, a certain lawyer stood up, and tempted him, saying, Master, what shall I do to inherit eternal life? He said unto him, What is written in the law? how readest thou? And he answering said, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind; and thy neighbour as thyself. And he said unto him, Thou hast answered right: this do, and thou shalt live.