Then Adam had intercourse with his wife, and she became pregnant. She bore a son and said, “By the Lord's help I have gotten a son.” So she named him Cain.
I will make you and the woman hate each other; her offspring and yours will always be enemies. Her offspring will crush your head, and you will bite her offspring's heel.”
Then at the east side of the garden he put living creatures and a flaming sword which turned in all directions. This was to keep anyone from coming near the tree that gives life.
We must not be like Cain; he belonged to the Evil One and murdered his own brother Abel. Why did Cain murder him? Because the things he himself did were wrong, and the things his brother did were right.