Members of the al-Qaida-affiliated Islamic State of Iraq and al-Sham appear in a new online video apologizing for beheading a man they thought was fighting for Syrian dictator Bashar al-Assad.

It turns out the dead man was part of Sunni rebel group fighting Assad's forces. The dead man's head was held up in a triumphant display in Aleppo.

A spokesman for the Islamic State of Iraq and al-Sham said the victim was injured in battle and thought he had been captured by Assad's forces. They claimed that he asked to be killed.

But, according to the video, which asked for "understanding and forgiveness," it's all good religiously. The spokesman said mistakes can happen while waging jihad. And he invoked a story in which the Muslim prophet Mohammad "said Allah would forgive a man who killed a believer in error," the Telegraph reported.