John 13:34-35
34"A new commandment I give to you, that you love one another, even as I have loved you, that you also love one another. 35"By this all men will know that you are My disciples, if you have love for one another."
Mark 12:29-33
29And Jesus answered him, The first of all the commandments is, Hear, O Israel; The Lord our God is one Lord:
30And thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength: this is the first commandment.
31And the second is like, namely this, Thou shalt love thy neighbour as thyself. There is none other commandment greater than these.
32And the scribe said unto him, Well, Master, thou hast said the truth: for there is one God; and there is none other but he:
33And to love him with all the heart, and with all the understanding, and with all the soul, and with all the strength, and to love his neighbour as himself, is more than all whole burnt offerings and sacrifices.
And million other examples in the New Testament. Read the whole Bible and you'll get the difference between New Testament and Old one, pre-Jesus and post.