Sahih Muslim , Book 5, Hadith 73 (In-Book) ⓘ
'Abdullah b. Shakhkhir narrated it on the authority of his father that he said prayer with the Messenger of Allah, and he spat and then rubbed it off with his left shoe.
وَحَدَّثَنِي يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنِ الْجُرَيْرِيِّ، عَنْ أَبِي الْعَلاَءِ، يَزِيدَ بْنِ عَبْدِ اللَّهِ بْنِ الشِّخِّيرِ عَنْ أَبِيهِ، أَنَّهُ صَلَّى مَعَ النَّبِيِّ صلى الله عليه وسلم قَالَ فَتَنَخَّعَ فَدَلَكَهَا بِنَعْلِهِ الْيُسْرَى .
also referenced under: Hadith 554 (Reference) & Book 4, Hadith 1128 (USC-MSA)