Prayer on a Ship
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 62
وَ سَأَلَ يُونُسُ بْنُ يَعْقُوبَ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلصَّلاَةِ فِي اَلْفُرَاتِ وَ مَا هُوَ أَصْغَرُ مِنْهُ مِنَ اَلْأَنْهَارِ فِي اَلسَّفِينَةِ فَقَالَ «إِنْ صَلَّيْتَ فَحَسَنٌ وَ إِنْ خَرَجْتَ فَحَسَنٌ» وَ سَأَلَهُ عَنِ اَلصَّلاَةِ فِي اَلسَّفِينَةِ وَ هِيَ تَأْخُذُ شَرْقاً وَ غَرْباً فَقَالَ «اِسْتَقْبِلِ اَلْقِبْلَةَ ثُمَّ كَبِّرْ ثُمَّ دُرْ مَعَ اَلسَّفِينَةِ حَيْثُ دَارَتْ بِكَ.
Yunus ibn Ya'qub asked Imam Jafar ibn Muhammad Al-Sadiq عليه السلام about praying in the Euphrates or smaller rivers while on a ship. Imam عليه السلام said: "If you pray (on the ship), it is good, and if you disembark to pray, it is also good." He further asked about praying on a ship that moves eastward and westward. He عليه السلام replied: "Face the Qiblah, say the takbir (opening declaration of prayer), and then turn with the ship wherever it turns."
- Ṣaḥīḥ al-Faqīh