Genesis 4:5-8 NIV

[5] but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast. [6] Then the LORD said to Cain, “Why are you angry? Why is your face downcast? [7] If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must rule over it.” [8] Now Cain said to his brother Abel, “Let’s go out to the field.” While they were in the field, Cain attacked his brother Abel and killed him.