The final verdict on a hadith, i.e. sahih (sound), hasan (good), da'if (weak) or maudu' (fabricated, forged), depends critically on this factor.
Among the early traditionists, mostly of the first two centuries, ahadith were classified into two categories only: sahih and da'if; al- Tirmidhi was to be the first to distinguish hasan from da'if. This is why traditionists and jurists such as Ahmad, who seemed to argue on the basis of da'if ahadith sometimes, were in fact basing their argument on the ahadith which were later to be known as hasan.65
We now examine in more detail these four important classes of ahadith.
