How can you (keep your wife) when she (the slave-woman) has claimed that she suckled both of you?
Authentic hadithعن عقبة بن الحارث رضي الله عنه مرفوعاً: «أنه تزوج أم يحيى بنت أبي إهاب، فجاءت أَمَة سوداء، فقالت: قد أرضعتكما، فذكرت ذلك للنبي صلى الله عليه وسلم . قال: فأعرض عني. قال: فَتَنَحَّيْتُ فذكرت ذلك له. قال: كيف وقد زعمت أن قد أرضعتكما؟!».
‘Uqbah ibn al-Hārith (may Allah be pleased with him) reported that he had married Umm Yahya bint Abi Ihāb. Then a black slave-woman came and said: "I suckled you both." I mentioned that to the Prophet (may Allah's peace and blessings be upon him) who turned his face aside. So I went to the other side and told him about it (again). He said: "How can you (keep your wife) when she (the slave-woman) has claimed that she suckled both of you?!"
Explanation
‘‘Uqbah ibn al-Hārith married Umm Yahya bint Abi Ihāb, then a black slave-woman came and told him that she had nursed him and his wife, and that they are thus siblings through nursing. He reported her statement to the Prophet (may Allah's peace and blessings be upon him) and said that she was lying. The Prophet (may Allah's peace and blessings be upon him) rebuked him for his wish to keep his wife despite the testimony of that slave-woman, saying to him: How can you do that after the woman has given her statement and testified what she knew?
Source · Narrated by Bukhari
From the Hadith Encyclopedia (hadeethenc.com).