Narrated Ibn Abbas:

(regarding the Verse):-- 'Cruel after all that, base-born (of illegitimate birth).' (68.13) It was revealed in connection with a man from Quaraish who had a notable sign (Zanamah) similar to the notable sign which usually-hung on the neck of a sheep (to recognize it).

حَدَّثَنَا مَحْمُودٌ، حَدَّثَنَا عُبَيْدُ اللَّهِ، عَنْ إِسْرَائِيلَ، عَنْ أَبِي حَصِينٍ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ عُتُلٍّ بَعْدَ ذَلِكَ زَنِيمٍ قَالَ رَجُلٌ مِنْ قُرَيْشٍ لَهُ زَنَمَةٌ مِثْلُ زَنَمَةِ الشَّاةِ.