Sahih Bukhari Volume 4, Book 52, Hadith Number 306.

Narated By Abu Huraira : Al-Hasan bin ‘All took a date from the dates of the Sadaqa and put it in his mouth. The Prophet said (to him) in Persian, “Kakh, kakh! (i.e. Don’t you know that we do not eat the Sadaqa (i.e. what is given in charity) (charity is the dirt of the people)).”