Chapter on the Hajj of Children
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 3|Chapter 92
وَ رَوَى صَفْوَانُ عَنْ إِسْحَاقَ بْنِ عَمَّارٍ قَالَ: سَأَلْتُ أَبَا اَلْحَسَنِ عَلَيْهِ اَلسَّلاَمُ عَنِ اِبْنِ عَشْرِ سِنِينَ يَحُجُّ قَالَ «عَلَيْهِ حَجَّةُ اَلْإِسْلاَمِ إِذَا اِحْتَلَمَ وَ كَذَلِكَ اَلْجَارِيَةُ عَلَيْهَا اَلْحَجُّ إِذَا طَمِثَتْ».
Safwan narrated from Ishaq ibn Ammar, who said: I asked Abu al-Hasan عليه السلام about a ten-year-old boy performing Hajj. Imam عليه السلام said: "The Hajj of Islam becomes obligatory upon him if he reaches puberty, and likewise for a girl—it becomes obligatory upon her when she begins menstruating."
- Ṣaḥīḥ al-Faqīh, p. 157