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Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
bukhari:836 – Muslim b. Ibrāhīm > Hishām > Yaḥyá > Abū Salamah > Saʾalt Abū Saʿīd al-Khudrī

I saw Messenger of Allah ﷺ prostrating in mud and water and saw the mark of mud on his forehead.  

البخاري:٨٣٦ – حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ قَالَ حَدَّثَنَا هِشَامٌ عَنْ يَحْيَى عَنْ أَبِي سَلَمَةَ قَالَ سَأَلْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ فَقَالَ

رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَسْجُدُ فِي الْمَاءِ وَالطِّينِ حَتَّى رَأَيْتُ أَثَرَ الطِّينِ فِي جَبْهَتِهِ