Likewise, if the person commanded is legally responsible—that is, an adult of sound mind—yet is unaware that killing is prohibited, such as someone raised outside Muslim lands, retaliation is taken from the one who issued the order. The commanded party is excused because of his ignorance, so liability rests with the instigator.
If, however, the commanded party is an adult of sound mind who does know that killing is forbidden, retaliation is taken from him, for he unlawfully carried out the killing himself. The Prophet ﷺ said, “There is no obedience to a creature when it entails disobedience to the Creator,” whether the commander is a ruler, a master, or anyone else. In this case the commander is subject to a discretionary punishment determined by the imam, because he has committed a sin and must be deterred.
When two people jointly and deliberately kill someone, and one of them lacks the conditions that make retaliation obligatory while the other meets them, retaliation is taken from the one who meets the conditions. He participated in an intentional, aggressive killing, whereas retaliation is waived from his partner because of a personal impediment, not because the cause of retaliation is deficient. Therefore it is imposed on the one against whom no legal obstacle exists. If one person restrains the victim for another until the latter kills him, the killer is executed and the one who held the victim is imprisoned until he dies.
Just as a single victim may demand retaliation from an entire group in cases of murder, he may do so as well in cases involving limbs or wounds. Thus, if several people severed a limb or inflicted a wound for which retaliation is due, and their individual actions cannot be distinguished—such as when they placed an iron object on someone’s hand and pressed together until the hand was cut off—all of their hands must be amputated. This is based on a report from ʿAlī (may Allah ennoble his face): two witnesses testified before him that a man had stolen, so he had the man’s hand cut off. Then they produced another man and said, “This is the thief; we were mistaken in…"