Sahih Bukhari Volume 003, Book 034, Hadith Number 268.
Narated By Abdullah bin Abu Mulaika : Uqba bin Al-Harith said that a black woman came and claimed that she had suckled both of them (i.e. 'Uqba and his wife). So, he mentioned that to the Prophet who turned his face from him and smiled and said, "How (can you keep your wife), and it was said (that both of you were suckled by the same woman)?" His wife was the daughter of Abu Ihab-al-Tamimi.