From Sahih Muslim (Hadith 3572):
A'isha (Allah be pleased with her) reported:There came to me Aflah b. Abu Qulais, my uncle by reason of fosterage; the rest of the hadith is the same (but with this) addition:" I ('A'isha) said (to the Holy Prophet): It was the woman who suckled me and not the man, whereupon he (Allah's Messenger) said: May your hands or your right hand be besmeared with dust (you were mistaken)
Reference: Muslim 3572