Mark 12:28-30 says:
28One of the teachers of the law came to Jesus. He heard Jesus arguing with the Sadducees* and the Pharisees.* He saw that Jesus gave good answers to their questions. So he asked Jesus, "Which of the commands is most important?"29Jesus answered, "The most important command is this: 'People of Israel, listen! The Lord our God is the only Lord.30You must love the Lord your God. You must love him with all your heart, all your soul, all your mind, and all your strength.'* (Easy-to-Read Version)
Sadducees A leading Jewish religious group. They accepted only the first five books of the Old Testament. They believed that people don't live again after death. Pharisees The Pharisees were a Jewish religious group that claimed to follow carefully all Jewish laws and customs. 'People ... strength' Quote from Deut. 6:4-5. 'You must ... yourself' Quote from Lev. 19:18.
King James Version: 28And 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? 29And Jesus answered him, The first of all the commandments is, Hear, O Israel; The Lord our God is one Lord: 30And 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.