Third: His words, “He will have his reward twice over,” because the man engaged in single combat, and this earned him one reward; then he killed himself in the path of Allah, and this earned him another reward.

The Messenger ﷺ also supplicated for him and did not say that he was required to offer expiation. Had expiation been obligatory upon him, the Prophet ﷺ would have made it clear, since there was a need to clarify it.

Moreover, when you read the verse, it becomes clear that what is meant is someone other than one who kills himself. For Allah Most High says:

“And whoever kills a believer by mistake must free a believing slave and pay blood-money to the victim’s family, unless they remit it.”

Blood-money and expiation are only combined where the person killed is someone other than the killer himself. As for one who kills himself, blood-money is unquestionably not due. Thus, the context of the verse indicates that it refers to one who kills another person. This view is more preponderant, though not on the basis of the verse, since someone may dispute its applicability, but on the basis of the account of Amir ibn al-Akwaʿ, may Allah be pleased with him.

His words, “whose life is inviolable,” mean one whose killing is forbidden. Those whose lives are inviolable fall into four categories: the Muslim, the dhimmi, the muʿāhad, and the mustaʾman. If someone kills a combatant unbeliever, however, he is not liable for either expiation or blood-money, because his life is not inviolable.

His words, “without right,” exclude the case in which a person is killed lawfully.

His words, “directly or by causation,” mean that one kills such a person either directly or indirectly. Direct killing is where one carries out the killing himself—for example, when someone intends to shoot game but strikes a person instead, or when he strikes him with a small stick and the person dies.

Causation is such as when someone digs a well in a place where he is not permitted to dig it