The greatest commandment is a biblical concept that refers to Jesus' response when asked which was the most important commandment in the law. In Matthew 22, Jesus quotes from the Old Testament book of Deuteronomy and states that the two greatest commandments are to love God with all your heart, soul, mind, and strength (Mark 12:30), and to love your neighbor as yourself (Mark 12:31). These two commands summarize the moral law and serve as a guide for how Christians should live their lives.