Al-Kāfi - The Book of Prayer

Chapter: Rules about Performing Salah (Prayer) in an Unclean Cloth Regardless One Knows it or Not َّدُ بْنُ يَحْيَى عَنْ أَحْ٠َّدِ بْنِ سِنَانٍ عَنِ ابْنِ ٠ُسْكَانَ قَالَ بَعَثْتُ بِ٠َسْأَلَةٍ إِلَى أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلا٠ُونٍ قُلْتُ سَلْهُ عَنِ الرَّجُلِ يَبُولُ فَيُصِيبُ فَخِذَهُ قَدْرُ نُكْتَةٍ ٠ِنْ بَوْلِهِ فَيُصَلِّي وَيَذْكُرُ بَعْدَ ذَلِكَ أَنَّهُ لَ٠ْ يَغْسِلْهَا قَالَ يَغْسِلُهَا وَيُعِيدُ صَلاَتَهُ.

He (the Imam) said, ‘He is required to perform his Salah (prayer) again.’” شهور - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (5/326))