Mattityahu 22:35-39

And one of them, a Baal Torah (learned Torah scholar, a Ben Torah), tried to trip up Rebbe, Melech HaMoshiach with a she'elah (question): Rabbi, which mitzvah is gedolah (great) in the Torah? 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). This is the gedolah and rishonah mitzvah. And the second mitzvah is like it: VAHAVTAH L'REIACHA KAMOCHA (And thou shalt love thy neighbor as thyself).