"Jesus replied, ‘You must love the LORD your God with all your heart, all your soul, and all your mind.’ This is the first and greatest commandment.”
Matthew 22:37-38 (NLT)

And we can be sure that we know him if we obey his commandments.  If someone claims, “I know God,” but doesn’t obey God’s commandments, that person is a liar and is not living in the truth.  But those who obey God’s word truly show how completely they love him. That is how we know we are living in him.  Those who say they live in God should live their lives as Jesus did.
1 John 2:3-6 (NLT)

"Dear friends, I am not writing a new commandment for you; rather it is an old one you have had from the very beginning. This old commandment—to love one another—is the same message you heard before.  Yet it is also new. Jesus lived the truth of this commandment, and you also are living it. For the darkness is disappearing, and the true light is already shining."
1 John 2:7-8 (NLT)

"Love your neighbor as yourself. I am the LORD."
Leviticus 19:18 (NLT)

"So now I am giving you a new commandment: Love each other. Just as I have loved you, you should love each other."
John 13:34 (NLT)

"The disciples began to ask each other which of them would ever do such a thing."
Luke 22:23 (NLT)