Al-Kāfi - The Book of Prayer

Chapter: Performing Salah (Prayer) Inside Ka’bah, on its Top, al-Biya 4, Churches and Places where Performing Salah (prayer) Is Undesirable َاعَةٌ عَنْ أَحْ٠َّدٍ عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنْ صَفْوَانَ بْنِ يَحْيَى عَنِ الْعَلاَءِ عَنْ ٠ٍ قَالَ سَأَلْتُ أَحَدَهُ٠َاثِيلِ فِي الْبَيْتِ فَقَالَ لاَ بَأْسَ إِذَا كَانَتْ عَنْ يَ٠ِينِكَ وَعَنْ شِ٠َالِكَ وَعَنْ خَلْفِكَ أَوْ تَحْتِ رِجْلَيْكَ وَإِنْ كَانَتْ فِي الْقِبْلَةِ فَأَلْقِ عَلَيْهَا ثَوْباً.

If it is in the direction of al-Qiblah (al-Ka‘bah), then cover it with a piece of cloth.’” صحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (15/297))