Musnad Ahmad 652:20

Muhammad ibn Abi ‘Adi narrated to us, from Dawud, from al-Sha‘bi, from al-Nu‘man ibn Bashir, who said: My father, Bashir ibn Sa‘d, carried me to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, bear witness that I have gifted al-Nu‘man such and such," mentioning a thing he named. He said: So he said: "Have you gifted all of your children the same as what you gifted al-Nu‘man?" He said: "No." He said: "Then take someone else as a witness besides me." He said: Then he said: "Does it not please you that they should be equal in their righteousness toward you?" He said: "Yes." He said: "Then do not [do it], then."