Mishkat al-Masabih 3 Purification كتاب الطهارة 210

وَعَن سَلمَة ابْن المحبق: أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي غَزْوَة تَبُوك أَتَى على بَيْتٍ فَإِذَا قِرْبَةٌ مُعَلَّقَةٌ فَسَأَلَ الْمَاءَ فَقَالُوا يَا رَسُولَ اللَّهِ إِنَّهَا مَيْتَةٌ: «فَقَالَ دِبَاغُهَا طهورها» . رَوَاهُ أَحْمد وَأَبُو دَاوُد

Salma b. al-Muhabbiq said that on the expedition to Tabuk [In the year 9 A.H.] God’s messenger came to a household, and seeing a bucket hanging, asked for water. They told him that the animal had died a natural death, but he replied, “Its tanning is its purification.” Ahmad and Abu Dawud transmitted it.