The Messenger of Allah ﷺ said, "The purification of a dead animal's hide is its tanning."
قال رسول الله ﷺ: زكاة الميتة دباغها.
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Nasai narrated it in Sunan Sughra (4258) and in Sunan al-Kubra (4559), and Tahawi in Sharh Maani (1/470), all of them through Abu Ghassan Malik bin Ismail, who said, Israil narrated to us, from Amash, from Ibrahim, from Aswad, from Ayesha, and he mentioned it. In one of the two wordings of Tahawi it reads, "Tanning the dead animal's hide is its purification." Its chain of transmission is sahih, Ibrahim being Ibn Yazid Nakhai, and Aswad being Ibn Yazid Nakhai.Sharik also narrated it from Amash, as found in Ahmad (25214), and there was disagreement over it, but what Israil narrated from Amash is the correct version.