٤ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ مُحَمَّدِ بْنِ إِسْمَاعِيلَ عَنْ بَعْضِ أَصْحَابِنَا عَنْ أَبِي الْحَسَنِ فِي طِينِ الْمَطَرِ أَنَّهُ لاَ بَأْسَ بِهِ أَنْ يُصِيبَ الثَّوْبَ ثَلاَثَةَ أَيَّامٍ إِلاَّ أَنْ يُعْلَمَ أَنَّهُ قَدْ نَجَّسَهُ شَيْ‏ءٌ بَعْدَ الْمَطَرِ فَإِنْ أَصَابَهُ بَعْدَ ثَلاَثَةِ أَيَّامٍ فَاغْسِلْهُ وَإِنْ كَانَ الطَّرِيقُ نَظِيفاً لَمْ تَغْسِلْهُ.
4. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn ’Isma‘il from certain persons of our people who have said the following: “I once asked abu al-Hassan , about soil which is found with rain water. He (the Imam) said, ‘It is not harmful up to three days unless it is found out to have become Najis (unclean) by something after rainfall. If such drops sprinkle after three days, then you must wash, but if the road is clean, then you do not need to wash.’” 