(51) بَابُ أَدَبِ الْوَالِدِ وَبِرِّهِ لِوَلَدِهِ
An-Nu'man ibn Bashir said that his father had carried him to the Messengerof Allah, may Allah bless him and grant him peace. He said, 'Messenger ofAllah, I testify to you that I have given an-Nu'man such-and-such. (It wasa slave). The Prophet asked, "Have you given each of your children the same"?""No," he replied. He said, "Then testify to someone other than me." Thenthe Prophet asked, "Do you not want to show equal kindness to all of them?""Indeed I do," he replied. He said, "Then do not do it."
Reference: Al-Adab Al-Mufrad 93
In-book reference: Book 5, Hadith 10
English translation: Book 5, Hadith 93