It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said regarding the skins of dead animals: "Tanning removes their filth and impurity."
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 2117
Hadith Gradingحکم دارالسلام:حسن، وفي سنده أخو سالم بن أبى الجعد، فيه جهالة.