Al-Kāfi - Volume 7 > The Matters Permissible in Endowment, Charity, Gift, Present, Providing Conditional Housing and Matters Permissible or otherwise for a Child and others
Hadith #9

9- مُحَمَّدُ بْنُ إِسْمَاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ الْحَجَّاجِ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فِي الرَّجُلِ يَجْعَلُ لِوُلْدِهِ شَيْئاً وَهُمْ صِغَارٌ ثُمَّ يَبْدُو لَهُ أَنْ يَجْعَلَ مَعَهُمْ غَيْرَهُمْ مِنْ وُلْدِهِ قَالَ لا بَأْسَ.

9. Muhammad ibn ’Isma‘il has narrated from al-Fadl ibn Shadhan from ibn abu ‘Umayr from ‘Abd al-Rahman ibn al-Hajjaj who has narrated the following: “About the case of a man who gives something to his small children then he decides to make his other children share it with them, abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘It is not harmful.’”