Linked from
The 133 pages that link to Hadith, each with the reason it gives.
ShariaBroader topic: Hadith collections preserve much of the material used to establish the Sunnah.
FiqhBroader topic: Hadith reports are a principal means of knowing the Sunnah.
Islamic lawBroader topic: Hadith reports preserve much of the Sunnah used in legal reasoning.
Sources of ShariaBroader topic: Hadith reports preserve much of the Sunnah used in legal reasoning.