Jesus commanded his disciples that they should love each other.

John 13:31-35

31 After Judas left, Jesus said, “Now it will be shown {my Father will show} how wonderful I, the one who came from heaven, am. And by what I do it will be seen {people will see} how great God is. 32 Since by what I do people will see how awesome God is, God himself will show people how awesome I am. And he will do that very soon.

33 You whom I love as though you were my children, I will continue with you only a short time longer. Then you will look for me, but I will not be here. Just like I told the Jewish leaders [SYN], I am telling you now, that where I am going, you cannot come yet. 34 Now I am giving you a new commandment: You must love each other. You must love each other in the way that I have loved you. 35 If you keep loving each other, everyone who is aware of that [HYP] will know that you are my disciples.”