Kiddushin 40 - Importance of Mitzvot
A certain noblewoman propositioned Rabbi Tzadok. He said to her: "My heart is weak and I can not do it. Is there anything to eat?" She said to him: "There is some non-kosher meat." He said to her: "What is to be deduced from this? That whoever performs this eats this."
She lit the oven and put the meat inside it. Rabbi Tsadok climbed up and sat inside the oven (he was allowed sacrifice his life because of his great stature). She said to him: "Had I known that you regard the matter as so severe, I would not have bothered you."