but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast.
Then the LORD said to Cain, “Why are you angry? Why is your face downcast?
References for Genesis 4:6
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.”
References for Genesis 4:7