All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If a Hadeeth meets the requirements of Saheeh Hadeeths known by scholars, and if this Hadeeth was not abrogated by a subsequent proof, then one must accept and act according to this Hadeeth. A person must not deny this Hadeeth, whether it is mentioned in both Saheeh Al-Bukhari and Saheeh Musim or in either one of them or in any other book. Denying such a Hadeeth is an act of obstinacy.
If a person denies such a Hadeeth, however, the person would not be a disbeliever, provided that he or she does not believe that the Prophet, sallallaahu ‘alayhi wa sallam , said this Hadeeth. This is the opinion of Is'haaq ibn Raahawayh and Ibn Al-Wazeer .
On the other hand, if a person denies a meaning of a Hadeeth, they would not be a disbeliever provided that the meaning does not refer to an indisputably established matter of religion which must be known to all Muslims.
In any case, if the scholars said that the Prophet, sallallaahu ‘alayhi wa sallam, said a certain Hadeeth, then a person must accept it and act according to it, whether this Hadeeth is mentioned by both Al-Bukhari and Muslim, by only one of them, or by other scholars, and whether the narrators of this Hadeeth are many or small in number.
One must not deny such a Hadeeth for any reason.
Allaah Knows best.