Sahih Muslim 999
Sahih Muslim · Book 12: The Book of Zakat · The virtue of spending and giving charity to relatives, spuses, children and parents, even if they are idolaters
Maimuna bint Harith reported that she set free a slave-girl during the lifetime of the Messenger of Allah (ﷺ) and she made a mention of that to the Messenger of Allah (ﷺ) and he said:
حَدَّثَنِي هَارُونُ بْنُ سَعِيدٍ الأَيْلِيُّ ، حَدَّثَنَا ابْنُ وَهْبٍ ، أَخْبَرَنِي عَمْرٌو ، عَنْ بُكَيْرٍ ، عَنْ كُرَيْبٍ ، عَنْ مَيْمُونَةَ بِنْتِ الْحَارِثِ ، أَنَّهَا أَعْتَقَتْ وَلِيدَةً فِي زَمَانِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ " لَوْ أَعْطَيْتِهَا أَخْوَالَكِ كَانَ أَعْظَمَ لأَجْرِكِ " .
Had you gives her to your maternal uncles, you would have a greater reward.