(a)Sunnah and hadith (the words, actions or approval that are narrated about Muhammad and which are believed to document Sunnah) are sometimes used synonymously, but not always.

For example the group known as “Ahl al-Hadeeth” is also sometimes called “Ahl as-Sunnah”; books such as “Kutub al-Hadeeth” are also sometimes called “Kutub as-Sunnah”, (according to the Saudi fatwa site "Islam Question and Answer"). In the context of biographical records of Muhammad, sunnah often stands synonymous with hadith since most of the personality traits of Muhammad are known from descriptions of him, his sayings and his actions from hadith.
Examples of where they are not used interchangeably but have different meanings are when Sunnah refers to the general affairs, i.e. the path, the methodology and the way of Muhammad; and to "adhering to Islam in the manner prescribed, without adding to it or introducing innovations into the religion", which hadith does not; fuqaha’ scholars use the word “Sunnah” when explaining the ruling on doing a specific action as being mustahabb (liked or encouraged), which they do not with hadith). According to Seyyed Nasr, the hadith contains the words of Muhammad, while the sunnah contains his words and actions along with pre-Islamic practices of which he approved.[ In the context of sharia, Malik ibn Anas and the Hanafi scholars are assumed to have differentiated between the two: for example Malik is said to have rejected some traditions that reached him because, according to him, they were against the "established practice of the people of Me