One day while the Messenger of Allah ﷺwas giving sermon he suddenly saw phlegm on the wall towards the qiblah(the direction to which Muslims turn in prayer) of the mosque. So he became angry at people. He then scraped it and sent for saffron and stained with it. He then said: When any one of you prays, Allah, the Exalted, faces him: he, therefore, should not spit before him.
بَيْنَمَا رَسُولُ اللَّهِ ﷺ يَخْطُبُ يَوْمًا إِذْ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ فَتَغَيَّظَ عَلَى النَّاسِ ثُمَّ حَكَّهَا قَالَ وَأَحْسِبُهُ قَالَ فَدَعَا بِزَعْفَرَانٍ فَلَطَّخَهُ بِهِ وَقَالَ إِنَّ اللَّهَ قِبَلَ وَجْهِ أَحَدِكُمْ إِذَا صَلَّى فَلاَ يَبْزُقْ بَيْنَ يَدَيْهِ