Call to Prayers (Adhaan)
10/151. Chapter:
No cleaning (rubbing) one's forehead and nose till one has completed As-Salat (the prayer)
قالَ أَبُو عَبْدِ اللَّهِ : رَأَيْتُ الحُمَيْدِيَّ يَحْتَجُّ بِهٰذَا الحَدِيثِ أَنْ لَا يَمْسَحَ الجَبْهَةَ فِي الصَّلاةِ.And Abu 'Abdullah said: I saw Al-Humaidi quoting this Hadith (No.798) to support his argument that the forehead should not be cleaned (rubbed) in As-Salat (prayer).
Sahih Bukhari
حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا هِشَامٌ، عَنْ يَحْيَى، عَنْ أَبِي سَلَمَةَ، قَالَ سَأَلْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ فَقَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَسْجُدُ فِي الْمَاءِ وَالطِّينِ حَتَّى رَأَيْتُ أَثَرَ الطِّينِ فِي جَبْهَتِهِ.
Narrated Abu Sa`id Al-Khudri: I saw Allah's Messenger (ﷺ) prostrating in mud and water and saw the mark of mud on his forehead.
Reference : Sahih al-Bukhari 836In-book reference : Book 10, Hadith 229USC-MSA web (English) reference : Vol. 1, Book 12, Hadith 798