Abu Dawud Book 9, Hadith Number 2806.

Narated By ‘Aisha : Some people of the desert came at the time of sacrifice in the time of the Apostle of Allah (PBUH). The Apostle of Allah (PBUH) said: Store up for three days and give the rest as sadaqah (alms). After that the people said to the Apostle of Allah (PBUH): Apostle of Allah, the people used to benefit from their sacrifices, take and dissolve fat from it, and make water-bags (from their skins). The Apostle of Allah (PBUH) said: What is that? or whatever he said: They said: Apostle of Allah, you have prohibited to preserve the meat of sacrifice after three days. The Apostle of Allah (PBUH) said: I have prohibited you due to a body of people who came to you. Now eat, give it as sadaqah (alms), and store up.