Sahih al-Bukhari 651
In-book no 651حَدَّثَنَا 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 صلى الله عليه وسلم يَسْجُدُ فِي الْمَاءِ وَالطِّينِ، حَتَّى رَأَيْتُ أَثَرَ الطِّينِ فِي جَبْهَتِهِ.
Narrated Abu Sa`id Al-Khudri: 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 Allah's Messenger (ﷺ)s prostrating in water and mud and even I saw the mark of mud on his forehead.