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.
(John 13:34-35)
In these verses, Jesus gives a well known command that is described as new. What is new about it? It's not the first time this command comes up in Jesus' teaching, never mind the Old Testament.
The newness is that our love for each other is to be based on Jesus’ love. "As I have loved you, you are also to love one another".
Our obedience to this command is not to earn Jesus love, his love comes first. Our obedience to this command is only possible due to Jesus’ love. How can I not forgive when I’ve been forgiven so much? Our love should look like his love - not sentimental feelings but sacrificial, true and compassionate.