GEN1257 Rav Shimshon Raphael Hirsch defines sinah as the feeling that the existence of a certain person is infringing upon your own existence, and that his disappearance would help to complete and fill what you are lacking. It is the feeling that you cannot find peace and security as long as he is around. Chorev.   He adds that sinah is related to the word סנה (sneh), a thorny shrub.   The soneh wants to act as a thorn and push the other person away from him. He views the other’s existence as a hindrance to his own success, and wishes him removed. His commentary on Bereshis 22:2.   This accurately describes the mechanics of hatred, but less intense hatred is also forbidden. The wish that the other person would cease to exist is demonstrated to an extreme in the hatred of Esav toward Yaakov. Rivka told Yaakov [this verse]. Rashi explains in the name of the Midrash that, in his (Esav’s) eyes Yaakov was already dead, and he drank the cup of consolation, which is customary for close relatives of the deceased to drink, over him. Esav’s hatred was so intense that he had felt as though Yaakov had already ceased to exist. CASTLE 514