Explanation of doubtful (unclear) things

Narrated Aisha: `Utba bin Abu Waqqas took a firm promise from his brother Sa`d bin Abu Waqqas to take the son of the slave-girl of Zam`a into his custody as he was his (i.e. `Utba's) son. In the year of the Conquest (of Mecca) Sa`d bin Abu Waqqas took him, and said that he was his brother's son, and his brother took a promise from him to that effect. 'Abu bin Zam`a got up and said, "He is my brother and the son of the slave-girl of my father and was born on my father's bed." Then they both went to the Prophet (ﷺ) Sa`d said, "O Allah's Messenger (ﷺ)! He is the son of my brother and he has taken a promise from me that I will take him." 'Abu bin Zam`a said, "(He is) my brother and the son of my father's slave-girl and was born on my father's bed." Allah's Messenger (ﷺ) said, "The boy is for you. O 'Abu bin Zam`a." Then the Prophet (ﷺ) said, "The son is for the bed (i.e. the man on whose bed he was born) and stones (disappointment and deprivation) for the one who has done illegal sexual intercourse." The Prophet (ﷺ) told his wife Sauda bint Zam`a to screen herself from that boy as he noticed a similarity between the boy and `Utba. So, the boy did not see her till he died.