Our mother Eve fell pregnant 20 times and, each time gave birth to twins—a brother and sister. Because it was the beginning of creation, their laws were different than ours now. The children of Prophet Adam and our mother Eve would marry each other but were prohibited to marry the sibling that they were conceived with in the same womb.
As Prophet Adam and our mother Eve’s children grew older, one of the oldest children was Cane (Qabil in Arabic), and one of the younger ones was Abel (Habil in Arabic). The older brother Cain was not very good looking, and his younger brother Abel was good looking. Prophet Adam instructed each brother to marry the other one’s sister. Cain’s sister was good looking, and Abel’s sister was not. So, Cain felt like he was getting the short end of the stick, no only was he not as good looking, but he had to marry one that isn’t very good looking either. So he refused to marry Abel’s sister and wanted to marry his own sister, conceived within the same womb.
He went to his father, Prophet Adam, peace be upon him, to complain. Prophet Adam got upset and made dua to Allah. Allah answered his dua by instructing both of the brothers to sacrifice something for Allah in charity by placing it on a particular mountain, and whomever Allah allows to marry that sister, Allah would accept their sacrifice by sending fire down to consume it. Since this was the beginning of creation, there were no poor people at the time to give charity, so this was how they would give charity and sacrifice something for Allah.
Abel, the young brother, was a Shepherd and brought a good healthy animal to sacrifice and placed it on the mountain. The older brother Cain left rotten produce to be sacrificed on the mountain. When they returned, they saw that only the younger brother’s sacrifice had been accepted, and the older brother’s sacrifice was still there and not accepted by Allah, the Glorious.
Instead of Cane thinking and pondering why his sacrifice was not accepted by Allah, he got upset and told his younger brother that he was going to kill him. His brother was jealous and envious of him since he was better looking, was going to marry a good-looking girl, and had his sacrifice accepted by Allah, and he had none of that. His younger brother Abel responded to him, saying that Allah only accepts from those who are pious, cautious, and fear Allah. He said if you attack me, I will not attack you back.
The Shaytan (devil) taught Cain how to kill, and he struck his bother and killed him. Then he paused and looked at his brother and realized the Shaytan (devil) had deceived him, and he felt regretful. He later returned to his brother’s body and saw a crow digging to bury another dead crow. So, he did the same to his brother. Then he grabbed his sister and went to a land far away from his father Prophet Adam, peace be upon him. They ended up having children, and corruption started to spread from their decedents. Prophet Adam, peace be upon him, was very distraught and upset that his son was killed as he loved him very much because he was a soft-hearted righteous son. So, Allah replaced him with another righteous son, Sheath, peace be upon him.