Matthew 22:38 KJV

This is the first and great commandment.
Matthew 22:38, King James Version

In context

37 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.

38 This is the first and great commandment.

39 And the second is like unto it, Thou shalt love thy neighbour as thyself.