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bukhari:669Muslim b. Ibrāhīm > Hishām > Yaḥyá > Abū Salamah > Saʾalt Abū Saʿīd al-Khudrī

A cloud came and it rained till the roof started leaking and in those days the roof used to be of the branches of date-palms. Iqama was pronounced and I saw Messenger of Allah ﷺs prostrating in water and mud and even I saw the mark of mud on his forehead.  

البخاري:٦٦٩حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ قَالَ حَدَّثَنَا هِشَامٌ عَنْ يَحْيَى عَنْ أَبِي سَلَمَةَ قَالَ سَأَلْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ فَقَالَ

جَاءَتْ سَحَابَةٌ فَمَطَرَتْ حَتَّى سَالَ السَّقْفُ وَكَانَ مِنْ جَرِيدِ النَّخْلِ فَأُقِيمَتِ الصَّلاَةُ فَرَأَيْتُ رَسُولَ اللَّهِ ﷺ يَسْجُدُ فِي الْمَاءِ وَالطِّينِ حَتَّى رَأَيْتُ أَثَرَ الطِّينِ فِي جَبْهَتِهِ