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. (Using translation from Muslim 548a)  

أَنَّ رَسُولَ اللهِ ﷺ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ فَحَكَّهَا بِيَدِهِ  

[Machine] That the Messenger of Allah, ﷺ , saw a bone in the direction of the mosque, so he scratched it with his hand.  

أَنَّ رَسُولَ اللهِ ﷺ رَأَى نُخَاعَةً فِي قِبْلَةِ الْمَسْجِدِ فَحَكَّهَا بِيَدِهِ  

[Machine] The Messenger of Allah ﷺ saw some dirt in front of the mosque, so he swept it away and smoothed its place.  

أَنَّ رَسُولَ اللهِ ﷺ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ فَحَكَّهَا وَخَلَّقَ مَكَانَهَا