Genesis 4:4-8

Abel brought the best parts from some of the firstborn of his flock. The LORD accepted Abel and his gift, but he did not accept Cain and his gift. So Cain became very angry and felt rejected. The LORD asked Cain, “Why are you angry? Why do you look so unhappy? If you do things well, I will accept you, but if you do not do them well, sin is ready to attack you. Sin wants you, but you must rule over it.” Cain said to his brother Abel, “Let’s go out into the field.” While they were out in the field, Cain attacked his brother Abel and killed him.