Sahih Bukhari Volume 5, Book 59, Hadith Number 484.

Narrated By Abdullah bin Abi Aufa : (Who was one of those who had given the Pledge of allegiance to the Prophet beneath the Tree) When the people brought Sadaqa (i.e. Rakat) to the Prophet he used to say, “O Allah! Bless them with your Mercy.” Once my father came with his Sadaqa to him whereupon he (i.e. the Prophet) said. “O Allah! Bless the family of Abu Aufa.”