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.” 

Source: Matthew 22:37-40 NIV

Comment.

Given in response to the question by a Rabbi; “What is the greatest commandment of all?”