Mattityahu 22:37, 39, 38, 40

And Rebbe, Melech HaMoshiach gave this teshuva (answer) to the Baal Torah, VAHAVTAH ES ADONOI ELOHEICHA BCHOL LEVAVCHA UVCHOL NAFSHECHA UVCHOL MODECHA (And thou shalt love the L-rd thy G-d with all thy heart and with all thy soul and with all thy might).

And the second mitzvah is like it: VAHAVTAH L'REIACHA KAMOCHA (And thou shalt love thy neighbor as thyself).

This is the gedolah and rishonah mitzvah.

On these two mitzvot hang the entire Torah and the Neviim.