Condition Two: The two limbs must be identical in name and location. Therefore, a right limb is never taken for a left, nor a left for a right—be that in hands, feet, eyes, ears, or the like—because each bears its own designation and performs a distinct function, and so they are not equivalent. Likewise, a little finger is not taken for a ring finger, for their names differ, and no principal (natural) limb is taken in exchange for a supernumerary one.

Condition Three: The offender’s limb and the victim’s must be equal in soundness and wholeness. A sound hand or foot is not taken for a withered one, nor a fully-fingered or fully-nailed hand or foot for one missing fingers or nails. A sound eye is not taken for a qāʾima eye—that is, an eye whose white and black are intact yet does not see—because they are unequal; nor is a speaking tongue taken for a mute tongue, owing to the latter’s deficiency. Conversely, a defective limb may be taken for a sound one: a withered hand for a sound hand, or a hand lacking fingers for a complete one. The defective limb shares the same basic form; its shortcoming is merely qualitative. Thus the victim recovers part of his right without injustice, and if he so chooses he may accept financial compensation instead of retaliation.

Retaliation in wounds:
Retaliation is carried out for every wound that reaches the bone, because precise equivalence can be achieved without excess or injustice. Examples include a muḍiḥa— a head or facial cut that exposes the bone— and wounds of the upper arm, shin, thigh, and foot. Allah the Exalted says, “and for wounds—retaliation” (5:45).

As for wounds that do not reach the bone, retaliation is not permitted for them, whether they are head wounds or otherwise—such as a jāʾifa, a penetrating injury that reaches the body cavity—