This is the great (most important, principal) and first commandment.
And He replied to him, You shall love the Lord your God with all your heart and with all your soul and with all your mind (intellect). [Deut. 6:5.]
And a second is like it: You shall love your neighbor as [you do] yourself. [Lev. 19:18.]
If you know these things, blessed and happy and to be envied are you if you practice them [if you act accordingly and really do them].