Water; Its Purity and Impurity
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 2
وَ سَأَلَ هِشَامُ بْنُ سَالِمٍ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلسَّطْحِ يُبَالُ عَلَيْهِ فَتُصِيبُهُ اَلسَّمَاءُ فَيَكِفُ فَيُصِيبُ اَلثَّوْبَ فَقَالَ «لاَ بَأْسَ بِهِ مَا أَصَابَهُ مِنَ اَلْمَاءِ أَكْثَرُ مِنْهُ.
Hisham ibn Salim asked Imam Jafar ibn Muhammad Al-Sadiq عليه السلام about a man urinating on a roof, then rain falls on it causing water to drip onto clothes. Imam عليه السلام said: "There is no harm in it as long as the water that hits it is more than the urine”.
- Ṣaḥīḥ al-Faqīh