Genesis 4:12

9 Yahweh said to Cain, "Where is Abel, your brother?" He said, "I don`t know. Am I my brother`s keeper?"

10 Yahweh said, "What have you done? The voice of your brother`s blood cries to me from the ground.

11 Now you are cursed because of the ground, which has opened its mouth to receive your brother`s blood from your hand.

12 From now on, when you till the ground, it won`t yield its strength to you. You shall be a fugitive and a wanderer in the earth."

13 Cain said to Yahweh, "My punishment is greater than I can bear.

14 Behold, you have driven me out this day from the surface of the ground. I will be hidden from your face, and I will be a fugitive and a wanderer in the earth. It will happen that whoever finds me will kill me."

15 Yahweh said to him, "Therefore whoever slays Cain, vengeance will be taken on him sevenfold." Yahweh appointed a sign for Cain, lest any finding him should strike him.