(13) باب النَّهْىِ عَنِ الْبُصَاقِ، فِي الْمَسْجِدِ فِي الصَّلاَةِ وَغَيْرِهَا
Abu Sa'id al-Khudri reported:
The Apostle of Allah (ﷺ) saw sputum sticking to the Qibla of the mosque. He scratched it off with a pebble and then forbade spitting on the right side or in front, but (it is permissible) to spit on the left side or under the left foot. (ID)
Reference (ID): Sahih Muslim 548 a (ID)
In-book reference (ID): Book 5, Hadith 63 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1118 (ID)