while Abel brought several choice lambs from the best of his flock. The LORD accepted Abel and his offering,
but he did not accept Cain and his offering. This made Cain very angry and dejected.
"Why are you so angry?" the LORD asked him. "Why do you look so dejected?
You will be accepted if you respond in the right way. But if you refuse to respond correctly, then watch out! Sin is waiting to attack and destroy you, and you must subdue it."
Later Cain suggested to his brother, Abel, "Let's go out into the fields." And while they were there, Cain attacked and killed his brother.
References for Genesis 4:8