Quran As The Meezan Over Sunnah
Good Question. The Foundations of Various Sunnah are indeed derived from the Quran. The Quran tells the believers to Offer Salat, Pay Zakat, Keep Fasting, Perform Hajj and even indicates that Previous Prophets and their Nations all established this Sunnah(Specially Prophet Ibraheem as Prophet Mohammad is told to follow his Sunnat). Had the Quran not mentioned the names of these Sunnat Ibadaat, i doubt we as Umaat would be able to preserve them. The guidance of the Quran compels us to look for the Methods to perform various Sunnats. And thats where we look to Concensus of Ummat in their Practice of these sunnat e Rasool. God Knows Best!