Genesis 27:41-42

41And Esau hated Jacob because of the blessing with which his father had blessed him. And Esau said in his heart, The days of mourning for my father are at hand, and I will slay my brother Jacob.

42And the words of Esau her elder son were told to Rebecca. And she sent and called Jacob her younger son, and said to him, Behold, thy brother Esau, as touching thee, comforts himself that he will kill thee.