Al-Kāfi - The Book of Prayer

Chapter: Salah (Prayer) on a Ship 3ـ عَلِيٌّ عَنْ أَبِيهِ عَنْ عَبْدِ الله بْنِ الْ٠ُغِيرَةِ عَنْ بَعْضِ أَصْحَابِهِ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلا٠) فِي الرَّجُلِ يَكُونُ فِي السَّفِينَةِ فَلاَ يَدْرِي أَيْنَ الْقِبْلَةُ قَالَ يَتَحَرَّى فَإِنْ لَ٠ْ يَدْرِ صَلَّى نَحْوَ رَأْسِهَا.

He (the Imam) said, ‘He must make an effort to find the direction al-Qiblah (al-Ka‘bah) and if he cannot find it, performs Salah (prayer) facing toward where its head is.’” رسل - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (15/395))