Shari'a is not just the Qur'an, you see Shari'a is comprised according to all the doctrines. There's consensus and analogy - argument by analogy. These are the four components in the Shari'a. An orthodox Sunni would not accept that the Shari'a was simply comprised of the Qur'an itself and actually there are people who say that it's heretical to believe that. They have to say that because if they don't say that then they would have to accept that, for example, stoning is not a punishment which appears in the Qur'an - it doesn't.