Sunnah.com reference : Book 7, Hadith 184English translation : Book 7, Hadith 0Arabic reference : Book 7, Hadith 928
A narration has:
My father went then to the Prophet (ﷺ) to call him as a witness to my Sadaqah (i.e. gift) and he asked, "Have you done the same with all your children?" He replied, "No." He said, "Fear Allah and treat your children equally." My father then returned and took back that gift.

[Agreed upon].
وَفِي لَفْظٍ : { فَانْطَلَقَ أَبِي إِلَى اَلنَّبِيِّ ‏- صلى الله عليه وسلم ‏-لِيُشْهِدَهُ عَلَى صَدَقَتِي.‏ فَقَالَ : " أَفَعَلْتَ هَذَا بِوَلَدِكَ كُلِّهِمْ"?.‏ قَالَ : لَا.‏ قَالَ: " اِتَّقُوا اَللَّهَ , وَاعْدِلُوا بَيْنَ أَوْلَادِكُمْ " فَرَجَعَ أَبِي, فَرَدَّ تِلْكَ اَلصَّدَقَةَ }  مُتَّفَقٌ عَلَيْه ِ  1‏ .‏‏1 ‏- هذه الرواية للبخاري ( 2587 )‏ ، ومسلم (1623)‏ (13)‏ والسياق لمسلم.‏