"A certain heathen came before Shammai and said to him, 'Make me a proselyte, on condition that you teach me the whole Torah while  standing on one foot.' Shammai repulsed him with the builder's cubit which was in his hand.  When the heathen went before Hillel, Hillel said to him, 'What is hateful to you, do not to your neighbour:  that is the whole Torah, the rest is commentary'" -- Talmud, Shabbat 31a