An-Nisa 4:92 وما كان لمومن ان يقتل مومنا الا خطا ومن قتل مومنا خطا فتحرير رقبة مومنة ودية مسلمة الى اهله الا ان يصدقوا فان كان من قوم عدو لكم وهو مومن فتحرير رقبة مومنة وان كان من قوم بينكم وبينهم ميثاق فدية مسلمة الى اهله وتحرير رقبة مومنة فمن لم يجد فصيام شهرين متتابعين توبة من الله وكان الله عليما حكيما ٩٢

And never is it for a believer to kill a believer except by mistake. And whoever kills a believer by mistake - then the freeing of a believing slave and a compensation payment [diyah] presented to his [i.e., the deceased's] family [is required], unless they give [up their right as] charity. But if he [i.e., the deceased] was from a people at war with you and he was a believer - then [only] the freeing of a believing slave; and if he was from a people with whom you have a treaty - then a compensation payment presented to his family and the freeing of a believing slave. And whoever does not find [one or cannot afford to buy one] - then [instead], a fast for two months consecutively,¹ [seeking] acceptance of repentance from Allāh.² And Allāh is ever Knowing and Wise.