Sahih Bukhari Volume 3, Book 48, Hadith Number 818.
Narated By An-Nu’man bin Bashir : My mother asked my father to present me a gift from his property; and he gave it to me after some hesitation. My mother said that she would not be satisfied unless the Prophet was made a witness to it. I being a young boy, my father held me by the hand and took me to the Prophet. He said to the Prophet, “His mother, bint Rawaha, requested me to give this boy a gift.” The Prophet said, “Do you have other sons besides him?” He said, “Yes.” The Prophet said, “Do not make me a witness for injustice.” Narrated Ash-Shabi that the Prophet said, “I will not become a witness for injustice.”