Sahih Muslim Book 003, Hadith Number 0707.
Chapter : Purification of the skins of the dead animals by tanning them.
Ibn Abbas reported: The Messenger of Allah (may peace be upon him) happened to pass by a goat thrown (away) which had been in fact given to the freed slave-girl of Maimuna as charity. Upon this the Messenger of Allah (way peace he upon him) said: Why did they not get its skin? They had better tan it and make use of it.