What is the ruling regarding fighters who shot at a car, thinking it belonged to the enemy, only to discover that it was carrying Muslims who had come to support them, bearing in mind that the shooting was collective during a fierce battle and that the cars of both sides were similar? Are they considered murderers, liable for blood money or expiation, and are the deceased considered martyrs?

If an error occurs in jihad and Muslims mistakenly kill another Muslim, there is no qisas (retribution in kind) or punishment for the perpetrator; rather, diyah (blood money) and kaffarah (expiation) are obligatory. Scholars differed regarding the obligation of diyah: some said it is to be paid from the Muslim treasury (Bayt al-Mal), others said it is incumbent upon those who were present at the incident, and still others said it is on the killer if the victim's guardians swear an oath, while some considered the death to be in vain. As for kaffarah, it is obligatory by unanimous agreement, because the killing was accidental.

Regarding whether the killed are martyrs: if they went out to uphold the word of Allah, then they are martyrs of the Hereafter. However, concerning worldly rulings (such as washing the body and offering the funeral prayer), if someone is accidentally killed in battle due to fighting disbelievers, scholars differed on this issue. The preponderant view is that he is a battlefield martyr who is not washed nor prayed over, because he was killed on the battlefield.