سورة An-Nisa ( The Women ) - الآية 92

It is not for a believer to slay another believer unless by mistake. And he who has slain a believer by mistake, his atonement is to set free from bondage a believing person and to pay blood-money to his heirs, unless they forgo it by way of charity. And if the slain belonged to a hostile people, but was a believer, then the atonement is to set free from bondage a believing person. And if the slain belonged to a (non-Muslim) people with whom you have a covenant, then the atonement is to pay the blood-money to his heirs, and to set free from bondage a believing person. But he who cannot (free a slave) should fast for two consecutive months. This is the penance ordained by Allah. Allah is All-Knowing, All-Wise.