The black flags will come from the East, led by mighty men, with long hair and beards, their surnames taken from their hometowns."
-- The Hadith (Prologue paragraph 4)

Importance: This is why ISIS carries a black flag today, as it believes it is the culmination of the prophecy. Zarqawi ('the man from Zarqa") and Baghdadi (even though his hometown is Samarra, not Baghdad) have evidently chosen their names out of belief that they fulfill the prophecy.

By Allah, we will come out. Forcibly, if God wills."
-- Abu Musab al-Zarqawi (Book I, Part 1 paragraph 7)

Importance: This reflects not only Zarqawi's determination to leave prison, but his belief in his own sense of destiny.

I knew at this moment that I would be hearing about him. This man was going to end up either famous, or dead."
-- Basel al-Sabha (Book 1, Part 2 paragraph 3)

Importance: Sabha, the physician at the al-Jafr prison, was stunned to see Zarqawi return to the facility to check up on fellow inmates after receiving amnesty. In awe of Zarqawi's...