It is narrated from Sayyiduna Nu'man bin Bashir (may Allah be pleased with him) that his father took him to the Messenger of Allah (peace and blessings be upon him) and said: I have given this son of mine a slave as a gift. The Messenger of Allah (peace and blessings be upon him) said: "Have you given a slave like this to every one of your children?" The father replied, No. So the Messenger of Allah (peace and blessings be upon him) said: "Then take it back from him."
Hadith Referenceالسنن المأثورة / باب ما جاء في فدية الأذى / 495
Hadith Takhrijصحیح بخاری، الهبة، باب الهبة للولد، رقم: 2586، صحیح مسلم، الهبات، باب كراهة تفضيل بعض الاولاد فی الهبة، رقم: 1623۔