Sahih Muslim Book 5, Hadith Number 2351.
Chapter : Accepting of gift by the Holy Prophet (may peace be upon him) and refusing the Sadaqa.
Anas b. Malik reported that Barira presented to the Apostle of Allah (may peace be upon him) a piece of meat which had been given to her as sadaqa. Upon this he (the Holy Prophet) said: That is a Sadaqa for her and a gift for us.