To tell you the truth I'm sick of Traditionalists and even some Quranists equating Sunnah with the Hadeeth. Sunnah has a lot of different meanings to different specialists in different branches of Islamic theology. To some it is only the superagatory practices to others it is the second face to the coin of islam itself.
In essence most people understand sunnah to mean uswah (example), and ths refers to the uswah hasanah of the messenger of God, i.e. last prophet Muhammad (although this can apply to all messengers of God). (sas)
We are also told in the Quran to follow the uswah of prophet Abraham (sas) as well, yet no one has tried to dredge up hadeeths about Abraham, NOT EVEN from the Bible where such hadeeths already exist. I find this telling.
In the end, I take the sunnah of the last prophet from the Quran. The Quran tells us what he said (by saying 'say') and what he did, and how he was (for instance the passage law kunta fadh-dhan la-infaddoo min hawlika: If you had been harsh they would have broken away from you).
So as a Quranist I am content with getting the Sunnah (as most understand this term) from the Quran. And to me Hadeeth DOES NOT equal Sunnah. Although I know Sunnis seriously don't like this idea.
Allah commands us in the Qur'an numerous times to Obey Him and the Messenger (PBUH), therefore you need to follow the hadeeth otherwise you wouldn't be obeying Allah. Furthermore it does not detail how to pray salah in the Qur'an, the detail of the actions is found in the Hadeeth, so if you didn't follow the Hadeeth you wouldn't know how to pray salah.
The Quran tells us to obey the messenger (that particular passage specifies obeying his commands as it concerns spoils of war) and to follow his uswah. Both of these can be done by following the message that was given to the prophet Muhammad (saas) and which he gave to us. THE QURAN DOES NOT SAY FOLLOW ANY HADEETH OTHER THAN THE QURAN ITSELF.
Anyone can pray (salaat). Even the pagans prayed (they made salaat). The Quran gives us examples of how to pray and tells us to do things like qiyaamah (standing up for prayer), rukoo3 (bowing or prostrating or both, as well as being humble) and sujood (worshipping as well as bowing or prostrating or both). This is all you need to know. In the end it appears that the traditional formula of Salat of the Muslims was either borrowed from Jews or it was invented. Whether it was invented or borrowed from Jews by the last prophet or not we'll never really know. In this case it makes it a sunnah practice, something that we CAN do but do not have to do. There is a case to be made that the form of Salat that most Muslims practice is a mutawaatir pratice. However, there are some problems with the definitions of the terms used with Salaat. Lisanul-Arab and Taj al-Arous define rak3ah in two ways. the first and most basic meaning is a one time bowing/prostration or humbling (rak3a also means to become poor or humbled). The meaning that would pertain to the basic practice of traditional salat does not describe a rak3ah as Muslims perform it today. The rak3ah of the most authentic lexicons is to stand once and then to bow down (with hands on knees) and then prostrate twice. It does not say 'to stand, bow to ones knees to stand again and then to prostrate twice) So it would seem that someone added a standing after the bowing that was not originally there. If you can find hadeeths where the traditional formula for Islamic prayer is explained in detail with every movement and term explained and in what order I think you may be the first man (or woman) EVER to do this. Most Muslims take many of the definitions of these terms for granted and have not researched their real or original meanings.