A new commandment I give to you, that you love one another, just like I have loved you. (John 13:34)
Honestly, it’s not that quite new. Hillel’s Golden Rule was known before, if the story really did happen. A fact is that is was commonly known that this rule was the most important according to human behavior. It was the second part of the Great Commandment.
When John in his letters spoke of the brotherly love and the love of God etc. and when he spoke explicitly about the new commandment, he obviously had this “great commandment” in mind. Looking to the rule of Hillel it’s the core of all the commandments together. It was a one-word description of the whole Torah.
Brothers, I write no new commandment to you, but an old commandment which you had from the beginning. The old commandment is the word which you heard from the beginning. (1John 2:7)
It fits perfectly in the rule of Hillel when it is told to gentiles. This is the first thing they have to do. A gentile who was about to come to a complete new environment of Jewish practices, was positively welcomed by Hillel and stimulated to “go and learn”. Here a gentile was welcomed to learn Torah.
There was a New Commandment, a new entry for the gentile people. Jesus advocated this. And to add some practical laws to it, the apostles also gave the Seven Laws of Noah (or at least some rules based upon that) by the apostolic convent. (Acts 15) They clearly make a distinctive reduced set of rules for gentiles who joined the people of Israel. But the Great Commandment applies to all mankind and has all the other rules in it as it were.
Now, since the Messiah Jesus from God and the Holy Spirit, applies that great and so special love from heaven into the very heart of his people, by this love we are about to live as we first were dead. This pure love answers the commandment of love exceedingly perfect.
John also taught the rule of Hillel in his own version:
Again, I write a new commandment to you, which is true in him and in you; because the darkness is passing away, and the true light already shines. He who says he is in the light and hates his brother, is in the darkness even until now. He who loves his brother remains in the light, and there is no occasion for stumbling in him. But he who hates his brother is in the darkness, and walks in the darkness, and doesn’t know where he is going, because the darkness has blinded his eyes. (1John 2:8-11)