In a macabre twist of fortune, a Syrian rebel group battling the Islamic State released a bloody video showing the brutal slaughter of ISIS fighters while the executioners don the infamous orange jumpsuits usually reserved for victims of the jihadist organization.The Syrian rebels, calling themselves Jaysh Al-Islam or the "Army of Islam," composed of approximately 25,000 soldiers following the unification of 60 rebel factions, can be seen making the captured ISIS fighters kneel before their gruesome deaths while one rebel announces: "Allah did not make a disease without appointing a remedy to it."The Islamic State fighters, dressed in all black, are then made to drink something before their executioners shoot the jihadists in the back of the head at point blank range with shotguns. As the lurid clip continues to play, a Jaysh Al-Islam militant says: "The most serious calamity for our jihad today is a group of people who grow at a time of division among Muslims."This group claimed to be the mother state and made Takfir [accusations of apostasy] on other Muslims, shed their blood and looted their properties and dignities."Jaysh Al-Islam, a reportedly Saudi-funded rebel faction fighting against Bashar Assad's loyalist army, is based out of Damascus and possesses an impressive array of armored tanks and weaponry, according to The Guardian. Jaysh Al-Islam, engineered in part by Saudi Arabia, who is alarmed at the influx of jihadist fighters entering into Syria, is led by Sheikh Zaharan Aloush, a militant Salafist released from prison in 2011 in the aftermath of the Syrian Civil war.