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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The statement which you referred to in the question is apparently false and there is no need to refute it. Indeed, the whole Muslim nation, in the past and in the present, agreed in a consensus that Abu Hurayrah was one of the Companions of the Prophet, sallallahau ‘alayhi wa sallam, and that Al-Bukhari and Muslim, were among the Imaams of guidance. So, those who degrade them in the last times do not harm them in any way.
In addition to this, if the person who said this lie was just and fair, he should have followed a scientific approach in proving his claims by providing evidence and proofs about his claims, otherwise any person can be good at providing allegations. Needless to say, if there is no proof for the claims, these claims are untrue and unfounded and remain only claims.
Finally, we advise our Muslim brothers in the East and West not to waste their time in reading books and articles of the people of falsehood, especially if a person does not have sufficient Islamic knowledge to refute their misconceptions as this may harm him more than it may benefit him.
We ask Allaah to protect us from this.
Allaah Knows best.