The Book of al-Fara' and al-'Atirah
41/4. Chapter:
The Skin Of Dead Animals (Those Not Slaughtered Or Killed Properly)
Sunan an-Nasai
أَخْبَرَنَا قُتَيْبَةُ، وَعَلِيُّ بْنُ حُجْرٍ، عَنْ سُفْيَانَ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنِ ابْنِ وَعْلَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَيُّمَا إِهَابٍ دُبِغَ فَقَدْ طَهُرَ " .
It was narrated that Ibn 'Abbas said: "The Messenger of Allah said: 'Any skin that is tanned has been purified."'
Reference : Sunan an-Nasa'i 4241In-book reference : Book 41, Hadith 20English translation : Vol. 5, Book 41, Hadith 4246