Sunan an-Nasa'i, Hadith 4241 ⓘ
It was narrated that Ibn 'Abbas said: "The Messenger of Allah said: 'Any skin that is tanned has been purified."'
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 " .
also referenced under: Book 41, Hadith 20 (In-Book) & Volume 5, Book 41, Hadith 4246 (DarusSalam)