Prayer During Travel
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 59
وَ سَأَلَهُ أَبُو بَصِيرٍ: عَنِ اَلرَّجُلِ يُصَلِّي فِي اَلسَّفَرِ أَرْبَعَ رَكَعَاتٍ نَاسِياً قَالَ «إِنْ ذَكَرَ فِي ذَلِكَ اَلْيَوْمِ فَلْيُعِدْ وَ إِنْ لَمْ يَذْكُرْ حَتَّى يَمْضِيَ ذَلِكَ اَلْيَوْمُ فَلاَ إِعَادَةَ عَلَيْهِ.
Abu Basir asked Imam Jafar ibn Muhammad Al-Sadiq عليه السلام about a man who, while traveling, prays four rak'ahs (instead of two) out of forgetfulness. The Imam said: "If he remembers it on that same day, he should repeat (the prayer). If he does not remember until the day has passed, then there is no need for him to repeat it”.
- Ṣaḥīḥ al-Faqīh