Q. What does the sunnah say about a person who denies a hadith of the Prophet (saw)? For example you say to him that it is sunnah to do so and so, he in turn says there is no hadith that says this, but in fact there is. What should I do if I have to perform salaah behind this person?
A. Denying a hadith of the Prophet (S.A.S) is a major sin which can lead to kufr (as mentioned by many scholars), especially when it is made evident and shown to be an authentic tradition.
After a Sunnah/hadith have been made clear to a person, then it is not permissible for him to deny. It is possible that he may not wish to practice upon it by either giving preference to another tradition or by giving a valid and authoritative explanation to the tradition. In both cases, this action would not constitute denial or rejection of the said hadith. However, when this is not the case, and a person out of sheer obstinacy and arrogance denies or rejects a tradition which is established as being ‘a hadith’ or ‘a sunnah’ of the Prophet (S.A.S), then this action amounts to deviation and you should avoid performing salaah behind him.
And Allah knows best.
Mufti Waseem Khan