The beard is dyed.
Let me take a minute to point out how hilarious this is. The dude supposedly is this ascetic, devout Muslim, but in actual fact, he's an image obsessed preener. I can't imagine that him evidently being so concerned about the color of his beard that he would dye it (while living in a cave, for God's sake) makes him look like anything less than a girlie-man (to steal Ahnold's phrase) in the men-are-men Middle East. And I'm thinking that in addition to trying to hunt him down, a sensible tactic would be for everyone to just make fun of the fact that he's obviously a total vanity queen.