Imam al-Shawkani (d. 1250 AH) writes in Fath al-Qadir: “The words, ‘But if he belonged to a people who are enemies to you and he was a believer, then the freeing of a believing slave is required’ (Q. 4:92) mean that the slain person is from a people at war with you—that is, the combatant unbelievers. This concerns a believer killed by Muslims while he is still living among the unbelievers from whom he came: he embraced Islam but did not emigrate, and the Muslims assumed he had not accepted Islam and remained on the faith of his people. In this case no blood money is due; rather, the killer must set free a believing slave.

Scholars differ over why the diyyah is waived. One opinion says it is because the victim’s heirs are unbelievers and therefore have no right to the blood money. Another holds that a believer who embraces Islam yet fails to emigrate enjoys only limited protection, citing Allah’s words: ‘As for those who believed but did not emigrate, you owe them no duty of protection at all’ (Q. 8:72). Other scholars maintain that the diyyah is nevertheless payable to the public treasury….” End quote.

Shaykh al-Islam Ibn Taymiyyah (d. 728 AH) comments: “This applies to a Muslim who remains among the unbelievers for a valid excuse—such as a captive—or to one who is genuinely unable to emigrate and leave their ranks. As for someone who voluntarily stands in their battle-lines, he bears no liability whatsoever, for he has exposed himself to destruction without excuse.”

The proof that the blood money for unintentional killing is borne by the killer’s ʿaqilah is the hadith of Abu Hurayrah: “The Messenger of Allah ﷺ ruled, concerning the stillborn child of a woman from the tribe of Lihyan who miscarried, that a ghurrah—namely a slave, male or female—be paid as compensation. Later the woman who was liable for the ghurrah died, and the Messenger of Allah ﷺ adjudged that her estate should go to her husband and her two daughters, while the ʿaql was to be borne by…”