The boy is shown in two segments (above) in the six minute film titled, "An Evening On The Banks Of The Tigris River In The Province Of Nineveh In The Islamic State", which was uploaded to YouTube and then quickly pulled down yesterday.
Foreign Policy reports children as young as six have been recruited to the ISIS-effort in Iraq and Syria and are being used as suicide bombers and "blood donours" for wounded fighters.
The video also marks the re-appearence of 17-year-old Australian Abdullah Elmir who had appeared in another propaganda video earlier this month.
Elmir smiles and struggles to keep a straight face throughout several minutes of prayers.
The teenager's Sydney parents have repeatedly condemned his actions after he told them he was going on "a fishing trip" in June and ended up fighting for ISIS in the Middle East.
"They (Elmir's parents) must be completely devastated, as I know many in this community are, by seeing their young people taken up in this," said Australia's Immigration Minister Scott Morrison at National Mosque Open Day last weekend.