The authority of the Sunna (hujjiyyat al-sunna)

For the jurists of usul the Sunna is the second root of rulings after the Book: obedience to the Prophet ﷺ is binding in what he commanded and forbade, and the Muslims agreed on this in his lifetime and after ¹². The source distinguishes what is certain — the mutawatir — from the ahad reports acted on by preponderant likelihood: no single hadith is ascribed to the Prophet with certainty unless mutawatir, while what inquiry into isnad and matn makes probable must still be followed ²³. The doubts raised against the Sunna's authority — its variants, its late recording — are dismissed as undetailed claims.