In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Abu Hurairah [radiyallaahu-anhu] said, “The Prophet [sallal laahu -alayhi wasallam] said, ‘There are two matters of Al-Jaahiliyyah [i.e. traits of pre-Islamic ignorance] and the people will never abandon them: wailing for the dead and reviling people’s lineages”.
In this hadeeth, there is a clear warning against falling into these two affairs, because they are from the deeds of Al-Jaahiliyyah [pre-Islamic ignorance]. The deeds of Al-Jaahiliyyah in most cases are evil because they are based on ignorance, a result of ignorance and emanate from ignorance. The best of all deeds are those that are from the Islamic legislation. Therefore, these two traits are from the deeds of the people Al-Jaahiliyyah, but it is not committed by all the people, rather some people will not leave them until the day of Judgement.
The first trait is wailing for the dead by raising one’s voice, an increased mention of [the dead person’s virtues], boasting, tearing one’s clothing and slapping one’s cheeks. All these are deeds of Al-Jaahiliyyah.
The second trait is reviling lineages by boasting about one’s lineage and reviling other people’s lineages, and this does not occur except due to pride and looking down on others. It is not from the traits of the people of Eemaan; rather humility is the trait of the people of Eemaan- being easy going, refraining from self-praise, [refraining] from reviling people’s lineages and [refraining from] boasting about one’s lineage. Indeed, Allaah said: [إِنَّ أَڪۡرَمَكُمۡ عِندَ ٱللَّهِ أَتۡقَٮٰكُمۡۚ – Verily, the most honourable of you with Allah is that (believer) who has more Taqwa]. [Sural Al-Hujuraat. Aayah 13]
At-taleeqaatul Maleehah Alaa Silsilah Al-Ahaadeeth As-Saheehah vol 1. Page 18. Slightly paraphrased