Al-Kāfi

Hadith 1571
marriage
3- حُمَيْدُ بْنُ زِيَادٍ عَنِ الْحَسَنِ بْنِ مُحَمَّدِ بْنِ سَمَاعَةَ عَنْ صَفْوَانَ بْنِ يَحْيَى عَنْ مُوسَى بْنِ بَكْرٍ عَنْ زُرَارَةَ عَنْ أَبِي جَعْفَرٍ (عَلَيْهِ السَّلام) قَالَ لا يُدْخَلْ بِالْجَارِيَةِ حَتَّى يَأْتِيَ لَهَا تِسْعُ سِنِينَ أَوْ عَشْرُ سِنِينَ.
3. Humayd ibn Ziyad has narrated from al-Hassan ibn Muhammad ibn Sama‘ah from Safwan ibn Yahya from Musa ibn Bakr from Zurarah from abu Ja'far (AS) who said: "One should not have sex with a female servant until she reaches nine years of age or ten years of age."
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī