I had some sheep at Uhud, and they began to die. I then entered upon Maymunah, wife of the Prophet (ﷺ), and mentioned it to her. Maymunah said to me: If you took their skins and made use of them, (that would be better for you). She asked: Is that lawful? She replied, Yes. Some people of the Quraysh passed by the Messenger of Allah (ﷺ) dragging a sheep of theirs as big as an ass. The Messenger of Allah (ﷺ) said to them: Would that you took its skin. They said: It died a natural death. The Messenger of Allah (ﷺ) said: Water and leaves of the mimosa flava purify it.
The letter of the Messenger of Allah (ﷺ) was read out to us in the territory of Juhaynah when I was a young boy: Do not make use of the skin or sinew of an animal which died a natural death.