Chapter on Water and Its Rules
Tahdhīb al-Aḥkām|Volume 1|Book 1|Chapter 21
مَا رَوَاهُ عَلِيُّ بْنُ جَعْفَرٍ قَالَ: سَأَلْتُ أَبَا الْحَسَنِ مُوسَى عَلَيْهِ السَّلَامُ عَنِ الْبَيْتِ يُبَالُ عَلَى ظَهْرِهِ وَيُغْتَسَلُ فِيهِ مِنَ الْجَنَابَةِ، ثُمَّ يُصِيبُهُ الْمَاءُ، أَيُؤْخَذُ مِنْ مَائِهِ فَيَتَوَضَّأُ لِلصَّلَاةِ؟ فَقَالَ: إِذَا جَرَى فَلَا بَأْسَ بِهِ.
Ali ibn Ja’far narrated: I asked Abu Al-Hasan Musa عليه السلام about a house where urine is poured on its roof, and ghusl (ritual purification) from janabah (major impurity) is performed there, and then water flows down from it. Can water from it be used for wudu (ablution) for prayer? Imam عليه السلام said: "If it flows, then there is no harm in it."
- Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 436
- Ṣaḥīḥ al-Tahdhīb