Allah mentions three categories in the verse: a believer; one under a covenant; and a believer who belongs to a people hostile to us.

Regarding the believer, Allah says: “The freeing of a believing slave and the payment of blood-money to his family.” Thus, two things are obligatory in his case: the freeing of a believing slave and blood-money delivered to his family.

The second is a believer from a people hostile to us. In his case, the expiation is due, but not the blood-money.

But who is this man who belongs to a people hostile to us while he is himself a believer?

Some scholars say that this refers to a Muslim man who stands in the ranks of the disbelievers, and so we kill him. In this case, no blood-money is due for him, because he was himself negligent concerning his own safety; however, we must offer the expiation.

Other scholars say that it refers to a man who is a believer but whose heirs are disbelievers. This is the correct and definitive view: he is a believing man whose heirs are disbelievers hostile to us. The expiation is obligatory in his case because he is a believer, but blood-money is not obligatory, for if we were to pay it to his family, they would use it to aid them in fighting the Muslims. Therefore, we do not pay it to them.

The third category is the one Allah mentions in His saying: “And if he was from a people with whom you have a treaty, then blood-money must be paid to his family, along with the freeing of a believing slave.” That is, if the person killed is a disbeliever under a covenant, then blood-money and expiation are due. This exists in our own time: if someone kills one of these non-Muslim workers by mistake, blood-money and expiation are obligatory.

Issue: Is expiation due for deliberate killing?

Some scholars say that deliberate killing entails an expiation, because if expiation is obligatory for accidental killing, then it is even more so in the case of deliberate killing, since deliberate killing is the graver sin,