Vayishlach - The Roots of Amalek

Chazal teach that Timna was a princess who wanted to join Avraham's Mishpacha, so she became a concubine by Eliphaz. Eliphaz was a Talmid of Yitzchak, arguably a chaver of Iyov. Yet between the two of them they had a son Amalek. Why would the root of all evil come from the best of Eisav's descendants? An amazing Yesod from Rav Tzadok Hakohen and the Ohr Hachaim Hakadosh, about how the greatest tumah is drawn to the greatest kedusha.