According to Bernard Haykel, a professor at Princeton University whose research focusses on Saudi Arabia’s Salafi movement, beards are sunnah, recommended but not required of Muslim men. Beard styles are a subject of intense discussion among Islamic scholars, Haykel told me when I spoke to him by phone. The specific length of a beard, the way it is trimmed, whether or not it is dyed: these distinctions make a deliberate statement about the wearer’s religious affiliations and the degree of his piety—or the degree of piety that he wishes to have imputed to him. “The Muslim Brotherhood wear it in a particular way,” Haykel said. “The Salafis wear it in a different way. The Hanafis wear it in yet another way.”

http://www.newyorker.com/news/daily-comment/a-saudi-woman-is-threatened-after-tweeting-about-beards – 2/19/2014