It is not lawful for a believer to kill another except by mistake. And whoever kills a believer unintentionally must free a believing slave and pay blood-money to the victim’s family—unless they waive it charitably. But if the victim is a believer from a hostile people, then a believing slave must be freed. And if the victim is from a people bound with you in a treaty, then blood-money must be paid to the family along with freeing a believing slave. Those who are unable, let them fast two consecutive months—as a means of repentance to Allah. And Allah is All-Knowing, All-Wise.
And whoever kills a believer intentionally, their reward will be Hell—where they will stay indefinitely.1 Allah will be displeased with them, condemn them, and will prepare for them a tremendous punishment.