Mattityahu 22:36-38

Orthodox Jewish Bible

³⁶ Rabbi, which mitzvah is gedolah (great) in the Torah?

³⁷ And Rebbe, Melech HaMoshiach gave this teshuva (answer) to the Baal Torah, VAHAVTAH ES ADONOI ELOHECHA 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 [DEVARIM 6:5]).

³⁸ This is the gedolah and rishonah mitzvah.