Tafsir Ibn Abbas: Al-Baqara, Ayah 178

O you who believe prescribed made obligatory for you is retaliation on equal terms regarding the slain both in the attributes of the one slain and in the action involved; a free man is killed for a free man and not for a slave; and a slave for a slave and a female for a female. The Sunna makes it clear that a male may be killed in retaliation for a female and that religious affiliation should be taken into account also so that a Muslim cannot be killed in return for an disbeliever even if the former be a slave and the latter a free man. But if anything of the blood is pardoned any one of those who have slain in relation to his brother the one slain so that the retaliation is waived the use of the indefinite shay’un ‘anything’ here implies the waiving of retaliation through a partial pardon by the inheritors of the slain; the mention of akhīh ‘his brother’ is intended as a conciliatory entreaty to pardon and a declaration that killing should not sever the bonds of religious brotherhood; the particle man ‘any one’ is the subject of a conditional or a relative clause of which the predicate is the following fa’ittibā‘un let the pursuing that is the action of the one who has pardoned in pursuing the killer be honourable demanding the blood money without force. The fact that the ‘pursuing’ results from the ‘pardoning’ implies that one of the two actions is a duty which is one of al-Shāfi‘ī’s two opinions here. The other opinion is that retaliation is the duty whereas the blood money is merely compensation for non-retaliation so that if one were to pardon but not name his blood money then nothing happens; and this latter is the preferred opinion. And let the payment of the blood money by the slayer to him the pardoner that is the one inheriting from the slain be with kindliness without procrastination or fraud; that stipulation mentioned here about the possibility of retaliation and the forgoing of this in return for blood money is an alleviation a facilitation given to you by your Lord and a mercy for you for He has given you latitude in this matter and has not categorically demanded that one of the said options be followed through in the way that He made it obligatory for Jews to retaliate and for Christians to pardon and accept blood money; and for him who commits aggression by being unjust towards the killer and slaying him after that that is after pardoning — his is a painful chastisement of the Fire in the Hereafter or of being killed in this world.