Dr Abd Al Kareem Zaydaan writes in his book: “There is no difference of opinion that the skin of a dead animal before it is tanned is unclean and impure, but when it is tanned it becomes pure if the animal from which the skin is pure when it was alive. This is one of the opinions preferred by Imam Ahmad, and in his another saying, no skin of a dead animal becomes pure after tanning, this opinion is the most common one attributed to the Maliki school of thought”.
Al Awza’i, ibn Mubarak, Abu Thawr and Ishaq bin Raahuwiya have said that the skin of the dead animals that are permissible to eat and slaughtered according to the Islamic law, become purified after tanning but other animal skins are not purified.
Al Shafi’ said that all animal skins become pure after tanning, apart from dogs, and pigs.
As for Abu Hanifah, all skins of animals are pure apart from pig skins.
Dawoud and the Zahiris school of thought (those who rely on outward meaning of texts), hold that all skins of dead animals are pure after tanning, including the skins of dog and pig with no exception. This is also an opinion reported from Abu Yusuf from Hanafis’ scholars.
Al-shawkani said on this last school of thought, that it is the most accepted, because the hadith that are mentioned regarding tanning do not differentiate between the skin of the dog and the skin of pigs. From these hadiths is the saying of Ibn Abbas: I heard Allah’s Messenger (ﷺ) say: “When the skin is tanned it becomes purified.” narrated by Muslim and others.
Aishah, may Allah be pleased with her, also said: The Prophet ﷺ commanded that the skins of animals which had died a natural death should be made use of after they had been tanned.
Al Darqatni gave record on the authority of Aisha RA that the Prophet ﷺ said: (Every tanned skin is pure).