“Love your fellow as yourself. The rest is commentary.”
I think this is a mash-up of two actual quotes:
“V’ohavto l’rei’acha kamocha – zeh k’lal gadol baTorah”
-Rabi Akiva
(A copied translation because I don’t know how to pronounce the Aramaic:)
“That which is hateful to you, do not do to your fellow. That is the whole Torah;
the rest is its explanation; go and learn.”
-Hillel Hazokein