حَدَّثَنَا مُحَمَّدٌ حَدَّثَنَا عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ فَحَتَّهَا ثُمَّ أَقْبَلَ عَلَى النَّاسِ فَقَالَ إِذَا كَانَ أَحَدُكُمْ فِي الصَّلَاةِ فَلَا يَتَنَخَّمْ قِبَلَ وَجْهِهِ فَإِنَّ اللَّهَ تَعَالَى قِبَلَ وَجْهِ أَحَدِكُمْ إِذَا كَانَ فِي الصَّلَاةِ
مسند امام احمد بن حنبل · Hadith 4841
It was narrated from Ibn 'Umar that the Messenger of Allah (PBUH) saw some sputum in the qiblah of the mosque. He scratched it then he turned to the people and said: "If one of you is praying, let him not spit in front of him, for Allah is in front of one of you when he prays.”
Sanad
حَدَّثَنَا مُحَمَّدٌ حَدَّثَنَا عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ