Congregational Prayer and Its Virtue
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 57
وَ سَأَلَ عَلِيُّ بْنُ جَعْفَرٍ أَخَاهُ مُوسَى بْنَ جَعْفَرٍ عَلَيْهِمَا اَلسَّلاَمُ: عَنِ اَلرَّجُلِ يَكُونُ خَلْفَ إِمَامٍ فَيَطُولُ فِي اَلتَّشَهُّدِ فَيَأْخُذُهُ اَلْبَوْلُ أَوْ يَخَافُ عَلَى شَيْءٍ أَنْ يَفُوتَ أَوْ يَعْرِضُ لَهُ وَجَعٌ كَيْفَ يَصْنَعُ قَالَ «يُسَلِّمُ وَ يَنْصَرِفُ وَ يَدَعُ اَلْإِمَامَ.
Ali ibn Ja'far asked his brother Imam Musa ibn Jafar Al-Kadhim عليه السلام about a man who is behind an Imam and the Imam prolongs the tashahhud, causing the man to feel the urge to urinate, fear missing something, or experience pain. What should he do? Imam عليه السلام replied: "He should perform the taslim (salutation of peace), leave, and leave the Imam."
- Ṣaḥīḥ al-Faqīh