Chapter on I'tikaf (spiritual Retreat)
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 2|Chapter 38
وَ رَوَى اَلْحَسَنُ بْنُ مَحْبُوبٍ عَنْ عَلِيِّ بْنِ رِئَابٍ عَنْ زُرَارَةَ قَالَ: سَأَلْتُ أَبَا جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ عَنِ اَلْمُعْتَكِفِ يُجَامِعُ قَالَ «إِذَا فَعَلَ ذَلِكَ فَعَلَيْهِ مَا عَلَى اَلْمُظَاهِرِ ». وَ قَدْ رُوِيَ: «أَنَّهُ إِنْ جَامَعَ فِي اَللَّيْلِ فَعَلَيْهِ كَفَّارَةٌ وَاحِدَةٌ وَ إِنْ جَامَعَ بِالنَّهَارِ فَعَلَيْهِ كَفَّارَتَانِ.
It is narrated by Al-Hasan ibn Mahbub, from Ali ibn Ri'ab, from Zurara, who said: "I asked Abu Ja'far عليه السلام about the ruling on an individual performing i'tikaf who engages in sexual relations. Imam عليه السلام said: 'If they do so, they incur the same penalty as one who has taken a vow of zihar (atonement).'" It has also been narrated: "If they engage in sexual relations during the night, they must pay one expiation. However, if they engage in sexual relations during the day, they must pay two expiations."
- Ṣaḥīḥ al-Faqīh, p. 112