It was narrated that 'Aishah said:
Ibn Zam'ah andSa'd (Ibn Abu Waqqas) referred a dispute to the Prophet concerning the son of Zam'ah's slave woman. Sa'd said : " O Messenger of Allah my brother (Utbah bin Abu Waqqas) left instructions in his will that when I come to Makkah, I should look for the son of the slave woman of Zam'ah and take him into my care." 'Abd bin Zam'ah said: "He is my brother and the son of the slave woman of my father; he was born on my father's bed." The Prophet ffi saw that he resembled 'Utbah, and said: "He belongs to you, O 'Abd bin Zam'ah. The child is for the bed. Observe Hijab before him, O Saudah." (sahih)
English reference: Vol. 3, Book 9, Hadith 2004
Arabic reference: Book 9, Hadith 2082