Hadithcore
Mishkat al-Masabih, 1935

Maimuna daughter of al-Harith told that she set free a girl in the time of God’s messenger, and when she mentioned that to him he said, “If you had given her to your maternal uncles it would have increased your reward.” (Bukhari and Muslim.)

وَعَنْ مَيْمُونَةَ بِنْتِ الْحَارِثِ: أَنَّهَا أَعْتَقَتْ وَلِيدَةً فِي زَمَانِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: «لَوْ أَعْطَيْتِهَا أخوالك كَانَ أعظم لأجرك»

References1 variant
In-Book Reference
Book 6, Hadith 160