Genesis 4:10-15

Then the LORD said, “What have you done? Your brother’s blood is crying out to me from the ground. And now you will be cursed in your work with the ground, the same ground where your brother’s blood fell and where your hands killed him. You will work the ground, but it will not grow good crops for you anymore, and you will wander around on the earth.” Then Cain said to the LORD, “This punishment is more than I can stand! Today you have forced me to stop working the ground, and now I must hide from you. I must wander around on the earth, and anyone who meets me can kill me.” The LORD said to Cain, “No! If anyone kills you, I will punish that person seven times more.” Then the LORD put a mark on Cain warning anyone who met him not to kill him.