explained that Islamic law is based on two textual sources: the Quran and the Sunnah, or the example of the Prophet Muhammad, gathered in many tens of thousands of fragments from the Prophet's life and sayings. Certain rules—not many—come from the unambiguous legislative content of the Quran, he said, and he cannot do anything about them even if he wants to. But those sayings of the Prophet (called Hadith), he explained, do not all have equal value as sources of law, and he said he is bound by only a very small number whose reliability, 1,400 years later, is unimpeachable.