Musnad Ahmad 1153:240

Yahya narrated to us, from Malik, who said: Abdullah ibn Abi Bakr narrated to me, from Amrah, from Aisha, who said: "A group of people from the desert dwellers arrived near the time of Adha. The Prophet, peace and blessings of Allah be upon him, said: 'Eat and store for three days.' When that time had passed, they said: 'O Messenger of Allah, people used to benefit from their sacrifices; they would render the fat from them and make water skins from them.' He said: 'And what is that?' They said: 'That which you forbade regarding keeping the meat of the sacrifices.' He said: 'I only forbade it because of the group that arrived. So eat, give in charity, and store.'"