Al-Kāfi - Volume 6 > Lowering for Girls
Hadith #3

عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ هَارُونَ بْنِ مُسْلِمٍ عَنْ مَسْعَدَةَ بْنِ صَدَقَةَ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ خَفْضُ الْجَارِيَةِ مَكْرُمَةٌ وَ لَيْسَتْ مِنَ السُّنَّةِ وَ لَا شَيْئاً وَاجِباً وَ أَيُّ شَيْ‏ءٍ أَفْضَلُ مِنَ الْمَكْرُمَةِ .

3. Ali ibn Ibrahim has narrated from his father from Harun ibn Muslim from Mas’adah ibn Sadaqah who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Reducing for girls is a noble trait but it is not of the Sunnah or obligatory; however, a noble trait is a very preferred matter.’”