God accepted the offering of Abel, but rejected Cain's. Angered by this rejection, Cain killed his brother, for which he was subjected to a double curse: The ground would no longer yield to him its wealth, and he was condemned to be a fugitive and a vagabond for the rest of his life.
God put a mark on Cain, so that no one who would come upon him would kill him. Cain settled in the land of Nod, east of Eden. Cain established a city and named it after his son Enoch (Genesis 4:1–17).
In the New Testament, Cain is seen as the opponent of his righteous brother Abel (Hebrews 11:4), as a symbol for an evil way of living (Jude, verse 11), and as someone whose works were wicked (1 John 3:12).
The famous saying "Am I my brother's keeper?" is said by Cain when the Lord asked him "Where is your brother Abel?" (Genesis 4:9).