Sheikh Khâlid al-Mâjid
Tanning makes lawful the use of the skins of unslaughtered food animals by the consensus of the jurists. They differ regarding the skins of animals that are not allowed to be eaten.
The strongest opinion is that tanning does not purify other than the hides of dead animals which would have been permissible to eat had they been properly slaughtered, such as cows and sheep. This is the opinion that has been related from `Alî and Ibn Mas`ûd.
This can also be extracted from what was authentically related from Ibn `Abbâs that a domestic animal (actually a sheep that had been kept as a house pet) belonging to Maymûnah died. The Prophet (peace be upon him) said : “Why did you not use its skin? Why don’t you tan it, because tanning its skin is like slaughtering it properly?”
The Prophet (peace be upon him) said: “The tanning of a hide is like slaughtering it.” [Sunan Abî Dâwûd, Sunan al-Nasâ’î, Sunan al-Bayhaqî, and Sahîh Ibn Hibbân. Ibn Hajar declared it authentic.]
Al-Shawkani explains that the phrase: “like slaughtering it” to mean that tanning purifies it and makes it permissible in the same way that slaughtering the animal does. This is an indication that the hides of dead animals do not become lawful by tanning except those of animals which are allowed to be eaten if legally slaughtering.
We also have the hadîth related by Abû Dawûd and al-Nasâ`î that al-Miqdâm bin Ma`dî Karib said to Mu`âwiyah: “I ask you by Allah, do you know that the Prophet (peace be upon him) forbade the wearing of the skins of predatory animals and using them for saddles?”
He answered: “Yes.”
There are many other narrations that support the meaning of this hadîth.
Since the skin of predatory animals is forbidden, then the skin of the pig is even more severely prohibited, since it is filth in and of itself.
Source: Islam Today