Related על עירובין 12:9

Said Rabbi Eliezer ben Rabbi Zadok: When I was studying Torah with Rabbi Yohanan the Horohite, I observed him eating his bread dry, for those were years of scarcity. I went and told my father, who said to me: Take him some olives. So I took some to him. He took them and looked at them; but when he saw that they were moist he said to me, I do not eat moist olives. So I went and told my father, who said to me, go and tell him that the olive (bottle) is perforated according to the laws of the school of Hillel, but the lees have stopped it up, to show that one may eat profane things from no impure motive. So though he was a disciple of the school of Shammai he was guided by the opinions of the school of Hillel.