Al-Maaida — Ruku 5

And recite to them the story of Adam's two sons, in truth, when they both offered a sacrifice [to Allah], and it was accepted from one of them but was not accepted from the other. Said [the latter], "I will surely kill you." Said [the former], "Indeed, Allah only accepts from the righteous [who fear Him].

If you should raise your hand against me to kill me - I shall not raise my hand against you to kill you. Indeed, I fear Allah, Lord of the worlds.

Indeed I want you to obtain [thereby] my sin and your sin so you will be among the companions of the Fire. And that is the recompense of wrongdoers."

And his soul permitted to him the murder of his brother, so he killed him and became among the losers.

Then Allah sent a crow searching in the ground to show him how to hide the disgrace of his brother. He said, "O woe to me! Have I failed to be like this crow and hide the body of my brother?" And he became of the regretful.

Because of that, We decreed upon the Children of Israel that whoever kills a soul unless for a soul or for corruption [done] in the land - it is as if he had slain mankind entirely. And whoever saves one - it is as if he had saved mankind entirely. And our messengers had certainly come to them with clear proofs. Then indeed many of them, [even] after that, throughout the land, were transgressors.

Indeed, the penalty for those who wage war against Allah and His Messenger and strive upon earth [to cause] corruption is none but that they be killed or crucified or that their hands and feet be cut off from opposite sides or that they be exiled from the land. That is for them a disgrace in this world; and for them in the Hereafter is a great punishment,

Except for those who return [repenting] before you apprehend them. And know that Allah is Forgiving and Merciful.