Kathir bin Frqd al-Madni كثير بن فرقد المدني · Clothing (Kitab Al-Libas)

On the expedition of Tabuk the Messenger of Allah (ﷺ) came to a household and, seeing a bucket hanging, asked for water. They said: Messenger of Allah, the animal died a natural death. He replied; Its tanning is its purification.