Narrated Ibn 'Abbas:

Regarding the Verse: "Verily! The worst of beasts in the Sight of Allah are the deaf and the dumb----those who understand not." (8.22) (The people referred to here) were some persons from the tribe of Bani 'Abd-Addar.

حَدَّثَنَا مُحَمَّدُ بْنُ يُوسُفَ، حَدَّثَنَا وَرْقَاءُ، عَنِ ابْنِ أَبِي نَجِيحٍ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ، إِنَّ شَرَّ الدَّوَابِّ عِنْدَ اللَّهِ الصُّمُّ الْبُكْمُ الَّذِينَ لاَ يَعْقِلُونَ قَالَ هُمْ نَفَرٌ مِنْ بَنِي عَبْدِ الدَّارِ.