>> that's the mosque we used to pray in, yes, yes. ♪ >> reporter: five times every day, devout muslims turn towards the holy city of mecca to pray. osama was always among them. >> for him it was a must. >> reporter: it is something of a mystery, why this son of a wealthy family was drawn to such rigid religious beliefs. over time batarfi saw his best friend become even more of a fundamentalist, striving to live according to his ultrastrict interpretation of the holy koran. >> no pictures, no music, and after that, not even tv. unless there's news. >> reporter: osama's religious devotion went beyond living a simple pious life.