They ask you concerning the sacred month about fighting in it. Say: Fighting in it is a grave matter, and hindering (men) from Allah's way and denying Him, and (hindering men from) the Sacred Mosque and turning its people out of it, are still graver with Allah, and persecution is graver than slaughter; and they will not cease fighting with you until they turn you back from your religion, if they can; and whoever of you turns back from his religion, then he dies while an unbeliever-- these it is whose works shall go for nothing in this world and the hereafter, and they are the inmates of the fire; therein they shall abide.

And it does not behoove a believer to kill a believer except by mistake, and whoever kills a believer by mistake, he should free a believing slave, and blood-money should be paid to his people unless they remit it as alms; but if he be from a tribe hostile to you and he is a believer, the freeing of a believing slave (suffices), and if he is from a tribe between whom and you there is a convenant, the blood-money should be paid to his people along with the freeing of a believing slave; but he who cannot find (a slave) should fast for two months successively: a penance from Allah, and Allah is Knowing, Wise.