Is leather from non-halal slaughter pure for prayer?

What the hadith says

The Prophet ﷺ said, "When the skin is tanned it becomes purified" (Sahih Muslim 366). In one report, Ibn Abbas was asked about skins brought by Magians, whose slaughtered meat the Muslims did not eat. He answered that the Prophet ﷺ had said tanning makes the skin pure (Sahih Muslim 366). In another, the Prophet ﷺ passed a dead sheep and asked, "Why don't you get the benefit of its hide?" When they said it was dead, he replied that only eating it is forbidden (Sahih al-Bukhari 1492).

So the meat and the hide are separate questions. Meat from an animal that was not slaughtered properly is not allowed to eat, but its tanned hide can be used.

What the schools say

• Hanafi: tanning purifies the hide of every animal except the pig.
• Shafi'i: tanning purifies every hide except that of the dog and the pig.
• Maliki and Hanbali: traditionally stricter. They said tanning does not fully purify the hide of an animal that died or was not slaughtered properly, though some of them allowed limited uses and others accepted the wider view.

The wider view rests on the clearest hadith, and it is the position of the Hanafi and Shafi'i schools, which many Muslims in the West follow.

What this means for your jacket and shoes

• Cow, sheep and goat leather: you can wear it and pray in it. You do not need to ask where it came from or how the animal died. Things are treated as pure unless you know otherwise.
• Pig leather: avoid it, since most scholars exclude pig skin even after tanning.
• If you follow a stricter school: choose synthetic leather or cloth for prayer, or ask your local imam what your school advises.
• Wet or sweaty leather: the leather itself stays pure. Only a real impurity on it, like urine, needs washing off.

Pig skin sometimes hides in cheap gloves, linings and wallets, so it is worth checking labels. See Can Muslims wear pigskin leather?

Common questions

Almost all commercial leather is tanned, so the hadith above settles the question for most people. Leather shoes are a separate matter, since keeping shoes on in prayer depends on where you are praying and whether they are clean. See Can I pray with my shoes on?

Fur and shearling follow similar rules, with an extra point about predators. See Is wearing real fur or sheepskin haram?