(13) باب النَّهْىِ عَنِ الْبُصَاقِ، فِي الْمَسْجِدِ فِي الصَّلاَةِ وَغَيْرِهَا
'A'isha reported:
The Apostle of Allah (may, peace be upon him) saw spittle or snot or sputum, sticking to the wall towards Qibla and scratched it off.
Reference: Sahih Muslim 549
In-book reference: Book 5, Hadith 65
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1120