At least the past 2,000 years the first saying is said... And it is an interpretation of the "commandment" Love your neighbor as yourself.
I see quite a few problems with this saying, today, in the 21st Century.
1. I know quite a few people that actually don't love themselves. I don't think they are capable of loving: loving is accepting people the way they are and the way they aren't. Love is not making another wrong for how they are.
They make themselves wrong, and everyone else.
The dynamic of making something or someone wrong is interesting.
The obvious and easily visible aspect is that if and when you make something wrong, you imply that you are better. That you know better. That you don't do that despicable thing they do... Which is B.S., if you catch my drift.
You do, and you yell, like the guy who points fingers at another when the room suddenly get stinky.
If we honored another oldie: "let the one who has never sinned throw the first stone!"
So asking of someone to treat another as well as they would treat themselves doesn't guarantee a loving treatment.
2. I know a few people that will give you so much, that will take care of you so well, that it will land as domination, the curtailing of your freedoms.
Mothers are really good at that. It is a secret "My way or the highway" dressed in goodness and kindness, but it's anything but good and kind.
I experience being loved only by touch. You can tell me all day you love me, I get that you want me to think that you do, and I am waiting for the other shoe to fall. Some people know that you love them by the gifts you do for them. You can give me gifts, and I will not think that you love me, I will not understand why you need to give me gifts I didn't want.
How you experience love depends on your dominant "modality:" I am kinesthetic and I experience the world through feelings and emotions. Being an empath is a kinesthetic psychic... l.o.l.
If you experience the world predominantly through your ears, then you are auditory, and you love to be told you are loved.
And if you are visual, then of course you need to see that you are loved, and gifts, flowers, decorations, parties, etc. will do the trick for you.
You see, it is not so simple to treat another with kindness and make them experience kindness...
Most of my friends are of a different modality, and I never experience being loved. Unless you touch me, or unless you do something for me that only you can do. Give me a ride, wash my dishes, sit patiently as I talk to you about what's important to me.
I am very lucky. I have an assistant who is exactly like that.