Man Lā Yaḥḍuruh al-Faqīh
Hadith 13171325 - 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.
Hadith.1325 - Yunus ibn Ya'qub asked Imam Jafar ibn Muhammad Al-Sadiq (as) about praying in the Euphrates or smaller rivers while on a ship.
Imam (as) 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 (as) replied: "Face the Qiblah, say the takbir (opening declaration of prayer), and then turn with the ship wherever it turns."