Abel was the second son of Adam and Eve and the first person whose murder is recorded in scripture. He brought an offering of the firstlings of his flock, which the Lord accepted, while his brother Cain’s offering of the fruit of the ground was not accepted; Cain grew angry, and at Satan’s instigation rose up and killed Abel in the field (Moses 5:18-33). The account states that Abel walked in holiness before the Lord and that Satan had commanded Cain to make the offering and then delivered Abel into his hands (Moses 5:26, 29). Cain swore an oath to Satan to keep the killing secret so that his father would not know of it (Moses 5:29-30). Abel died without posterity.
Helaman’s record names this same plot with Cain — that the murder of Abel “should not be known unto the world” — as the origin of the secret oaths and combinations that recurred among the Nephites, including those used by the Gadianton robbers in the decades before Christ’s birth (Helaman 6:27).