From the brief introduction to the nature of righteousness appearing in verses before this, the text now enters into the description of related subsidiary injunctions. Under the first injunction in this connection, the verse prescribes the law of Qisas (even retaliation), that is, the killer will be killed, irrespective of the status of the parties involved. If the aggrieved party somewhat relents on its own and forgives the Qisas قصاص ، but does not forgive the offence totally, it will become necessary for the killer to pay diyah (دیۃ) or blood-money as fixed, in a fair manner, and promptly. The claimant too, should pursue the matter in a recognized manner causing no harassment to the defendant. This law of blood-money and pardon is a relief granted by Allah Almighty in His grace, otherwise, there would have been no choice but to face the punishment of death. If, after all that, anyone crosses the limit set by Allah, such as, the filing of a false or doubtful case of murder, or a post-pardon re-opening of a murder case, he will be severely punished. In the end, the verse points out that wise people should have no difficulty in seeing that the law of even retaliation does not take life, instead, it gives life, for such a deterrent law will make people fear the punishment of killing somebody and thus lives will be saved.
There is life in 'Qisas' قصاص
Literally, the word, Qisas means likeness. In usage, it denotes 'even retaliation' or to return like for like. In Islamic juristic terminology, Qisas means the equal retaliation of an aggression committed against the body of a person. This retaliation is allowed only with a condition that the principle of "like for like" is strictly observed. This has been explained more clearly later on in verse 194 of this very Sarah which says:
فَاعْتَدُوا عَلَيْهِ بِمِثْلِ مَا اعْتَدَىٰ عَلَيْكُمْ
So, agress against him in the like manner as he did against you.
And also in the concluding verses of Surah al-Nahl, the same rule has been covered:
وَإِنْ عَاقَبْتُمْ فَعَاقِبُوا بِمِثْلِ مَا عُوقِبْتُم بِهِ
And, if you retaliate, then retaliate just as you have been oppressed against. (16:126)
Therefore, as a term of the Shari'ah, the Qisas قصاص is a punishment for killing or wounding in which the principle of equality or likeness is taken into full consideration.
Rulings
1. The principle of even retaliation is applied exclusively in cases of culpable homicide when someone has been killed intentionally with a lethal weapon causing injury and blood-loss.
2. In a homicide of this nature, the killer is killed in even retaliation - free man for a free man, slave for a slave, and female for a female - and similarly, a man for a woman. The mention of 'free man for a free man' and 'female for a female' in this verse refers to a specific event in the background of which it was revealed.
On the authority of Ibn Abi Hatim ؓ 1, Ibn Kathir (رح) has reported that, just before the advent of Islam, war broke out between two tribes. Many men and women, free and slaves, belonging to both, were killed. Their case was still undecided when the Islamic period set in and the two tribes entered the fold of Islam. Now that they were Muslims, they started talking about retaliation for those killed on each side. One of the tribes which was more powerful insisted that they would not agree to anything less than that a free man for their slave and a man for their woman be killed from the other side.
It was to refute this barbaric demand on their part that this verse was revealed. By saying 'free man for a free man, slave for a slave and female for a female' it is intended to negate their absurd demand that a free man for a slave and man for a woman should be killed in retaliation, even though he may not be the killer. The just law that Islam enforced was that the killer is the one who has to be killed in Qisas قصاص . If a woman is the killer why should an innocent man be killed in retaliation? Similarly, if the killer is a slave, there is no sense in retaliating against an innocent free man. This is an injustice which can never be tolerated in Islam.
This verse means nothing but what has been stated earlier, and we repeat, that the one who has killed will be the one to be killed in Qisas قصاص . It is not permissible to kill an innocent man or someone free for a killer, woman or slave. Let us hasten to clarify that the verse does not mean that Qisas قصاص will not be taken from a man who kills a woman or from a free man who kills a slave. In the very beginning of this verse the words الْقِصَاصُ فِي الْقَتْلَى: "The Qisas قصاص has been enjoined upon you in the case of those murdered" are a clear proof of this universality of application. There are other verses where this aspect has been stated more explicitly, for instance, in النَّفْسَ بِالنَّفْسِ (the person for the person).
3. If, in a case of intentional killing the murderer is given full pardon, for instance, should both of the two surviving sons of the deceased pardon and forego their right of retaliation, the killer is free of any claim against him. In case the pardon is not that full, for instance, as illustrated above, one of the two surviving sons does pardon the killer while the other does not, the result will be that the killer will stand released right there from the retaliatory punishment, but the one who has not pardoned the killer will be entitled to half of the blood-money (diyah). In Shari'ah, this diyah amounts to one hundred camels or one thousand dinars or ten thousand dirhams درھم or approximately nineteen pounds of silver according to current weights and measures.
4. The way an incomplete pardon makes payment of blood-money necessary, in the same manner, a mutual settlement between parties concerned on a certain amount makes retaliation inapplicable and payment of the agreed amount becomes necessary. This, however, is governed by some conditions which appear in books of fiqh فقہ .
5. Under the Islamic law, the inheritors of the person killed, whatever their number, will inherit and own the right of retaliation and blood-money in accordance with their share in the inheritance. If blood-money is taken, it will be distributed among the inheritors in accordance with their share in the inheritance. And should Qisas قصاص (even retaliation) become the choice, the right of Qisas قصاص will also be commonly shared by all. Since Qisas is indivisible, the pardon given by any one of the inheritors will hold good and the pardon will become inclusive of the right of retaliation held by other inheritors. However, they shall receive the blood-money amount according to their share.
6. It is true that the right of even retaliation is vested in the legal heirs of the persons killed but, in accordance with the consensus of the Muslim community, they do not have the right to settle the score all by themselves, in other words, they cannot kill the killer on their own, instead, they have to seek the help of a Muslim ruler or his deputy to realize their right. The reason is that Qisas قصاص is an intricate issue when it comes to details which are simply out of reach for an average person. Therefore, the legal heirs of the person killed, not knowing the particular circumstances when retaliation does, or does not become necessary, may commit some sort of excess under the heat of their anger. So, by a unanimous agreement of the scholars of the Muslim community, it is necessary that the right of retaliation be secured and made effective through the agency of an Islamic government. (Qurtubi)