Allah the Almighty revealed: And (0 Muhammad) recite to them (the Jews) the story of the two sons of Adam Abel and Cain - Habil and Qabil respectively in truth; when each offered a sacrifice (to Allah), it was accepted from the one but not from the other. The latter said to the former: "I will surely kill you."
The former said: "Verily, Allah accepts only from those who are Al-Muttaqeen (the pious). If you do stretch your hand against me to kill me, I shall never stretch my hand against you to kill you, for I fear Allah; the Lord of the Alamin (mankind, jinn, and all that exists). Verily I intend to let you draw my sin on yourself as well as yours, then you will be one of the dwellers of the Fire, and that is the recompense of the Zalimeen (polyt heists, and wrong-doers)."
So the Nafs (self) of the other (latter one) encouraged him and made fair-seeming to him the murder of his brother; he murdered him and became one of the losers. Then Allah sent a crow who scratched the ground to show him to hide the dead body of his brother. He (the murderer) said: "Woe to me! Am I not even able to be as this crow and to hide the dead body of my brother?" Then he became one of those who regretted. Surah 5:27-31