Chapter: The conditions for qiṣās (retaliatory execution) in cases of homicide

They are four:

1. Legal accountability (taklīf) of the killer. Thus, no qiṣās applies to a minor or an insane person; instead, the expiation (kaffārah) is taken from their own property, while the blood-money (diyah) is paid by their paternal relatives (ʿāqilah).

2. Protected status (ʿiṣmah) of the victim. No expiation or blood-money is owed for killing a combatant enemy, an apostate, or an adulterer who is muḥṣan, even if the killer is of the same sort.

3. Equivalence (mukāfaʾah): at the moment of the offense the killer must not have enjoyed superiority over the victim in Islam, freedom, or ownership⦗1⦘. Accordingly, a Muslim—even if he is a slave—is not executed for a non-Muslim, even if the latter is free; a free person—even if he is a dhimmī—is not executed for a slave, even if the slave is Muslim; nor is a mukātib executed for his own slave, even if that slave is a close blood-relative who is unmarriageable to him⦗2⦘.

And a free Muslim—whether male or female—is put to death for killing another free Muslim—male or female; likewise, a slave is executed for killing a fellow slave and for killing someone of higher status, and the same rule applies to a dhimmī.