Chapter on I'tikaf (spiritual Retreat)
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 2|Chapter 38
وَ فِي رِوَايَةِ مَنْصُورِ بْنِ حَازِمٍ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: «اَلْمُعْتَكِفُ بِمَكَّةَ يُصَلِّي فِي أَيِّ بُيُوتِهَا شَاءَ وَ اَلْمُعْتَكِفُ فِي غَيْرِهَا لاَ يُصَلِّي إِلاَّ فِي اَلْمَسْجِدِ اَلَّذِي سَمَّاهُ.
In a narration from Mansur ibn Hazim, from Abu Abdullah عليه السلام, it is reported: "The one performing i'tikaf in Mecca may pray in any of its houses as they wish. However, the one performing i'tikaf elsewhere must pray only in the specific mosque designated for their i'tikaf."
- Ṣaḥīḥ al-Faqīh, p. 111