Mark 12:28-31
And one of the scribes came up and heard them disputing with one another, and seeing that he answered them well, asked him, "Which commandment is the most important of all?" Jesus answered, "The most important is, 'Hear, O Israel: The Lord our God, the Lord is one. And you shall love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.' The second is this: 'You shall love your neighbor as yourself.' There is no other commandment greater than these."
John 13:34-35
A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another."
1 John 3:23
And this is his commandment, that we believe in the name of his Son Jesus Christ and love one another, just as he has commanded us.
Romans 13:8-10
Owe no one anything, except to love each other, for the one who loves another has fulfilled the law. For the commandments, "You shall not commit adultery, You shall not murder, You shall not steal, You shall not covet," and any other commandment, are summed up in this word: "You shall love your neighbor as yourself." Love does no wrong to a neighbor; therefore love is the fulfilling of the law.
Galatians 5:14
For the whole law is fulfilled in one word: "You shall love your neighbor as yourself."