Chapter on Tayammum and Its Rules
Tahdhīb al-Aḥkām|Volume 1|Book 1|Chapter 8
وَ بِهَذَا اَلْإِسْنَادِ عَنْ مُحَمَّدِ بْنِ يَعْقُوبَ عَنْ عِدَّةٍ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ عَلِيِّ بْنِ أَحْمَدَ رَفَعَهُ عَنْ أَبِي عَبْدِ اَللَّهِ عَ قَالَ: سَأَلْتُهُ عَنْ مَجْدُورٍ أَصَابَتْهُ جَنَابَةٌ قَالَ« إِنْ كَانَ أَجْنَبَ هُوَ فَلْيَغْتَسِلْ وَ إِنْ كَانَ اِحْتَلَمَ فَلْيَتَيَمَّمْ».
And through this chain of transmission from Muhammad ibn Ya‘qub, from a group of our companions, from Ahmad ibn Muhammad, from Ali ibn Ahmad, who raised it (the narration) from Abu ‘Abdullah عليه السلام:
I asked Imam عليه السلام about a person afflicted with smallpox who experienced janabah. Imam عليه السلام said: "If he became impure due to intercourse (intentional), then he must perform ghusl (ritual bathing), but if it was due to a nocturnal emission (ihtilam), then he should perform tayammum (dry ablution).”"
- Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 209
- Ṣaḥīḥ al-Tahdhīb