Imam Al-Nawawi’s Riyad-us-Saliheen
Chapter 275
Prohibition of Deriding one’s Lineage

Allah, the Exalted, says:

“And those who annoy believing men and women undeservedly, bear on themselves the crime of slander and plain sin.” (33:58)

1578. Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “Two matters are signs of disbelief on the part of those who indulge in them: Defaming and speaking evil of a person’s lineage, and wailing over the dead.”
[Muslim].