(Sky News) One of the various videos released by IS showing the beheading of hostages offers a fleeting glimpse of the ancient apocalyptic prophecy that fuels the group's extremism.
Peter Kassig, also known as Abdul-Rahman, was murdered and his head later displayed in a video that also shows the slaughter of captured Syrian soldiers and speech from a British-sounding IS militant dubbed 'Jihadi John'.
The militant says the killing took place in the town of Dabiq, adding: "Here we are burying the first American crusader in Dabiq, eagerly waiting for the remainder of your armies to arrive."
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The line is a reference to an ancient prophecy that an "infidel horde" would stage a monumental battle with an Islamic army in the Syrian town.
The Sunni Muslim tale dates back more than 1,300 years and tells of the "horde" flying 80 banners before an Islamic triumph that triggers the end of days.