Sunan an-Nasa'i, Hadith 3686 ⓘ
An-Nu'man said, when he was delivering a Khutbah: "My father took me to the Messenger of Allah to ask him to bear witness to a gift that he had given me. He said: 'Do you have any other children besides him?' He said: 'Yes.' He said: 'Treat them equally.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ حَاتِمٍ، قَالَ أَنْبَأَنَا حِبَّانُ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ فِطْرٍ، عَنْ مُسْلِمِ بْنِ صُبَيْحٍ، قَالَ سَمِعْتُ النُّعْمَانَ، يَقُولُ وَهُوَ يَخْطُبُ انْطَلَقَ بِي أَبِي إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم يُشْهِدُهُ عَلَى عَطِيَّةٍ أَعْطَانِيهَا فَقَالَ " هَلْ لَكَ بَنُونَ سِوَاهُ " . قَالَ نَعَمْ . قَالَ " سَوِّ بَيْنَهُمْ " .
also referenced under: Book 31, Hadith 15 (In-Book) & Volume 4, Book 31, Hadith 3716 (DarusSalam)