حَدَّثَنَا أَبُو سَلَمَةَ أَخْبَرَنَا لَيْثٌ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ وَهُوَ يُصَلِّي بَيْنَ يَدَيْ النَّاسِ فَحَتَّهَا ثُمَّ قَالَ حِينَ انْصَرَفَ مِنْ الصَّلَاةِ إِنَّ أَحَدَكُمْ إِذَا كَانَ فِي الصَّلَاةِ فَإِنَّ اللَّهَ عَزَّ وَجَلَّ قِبَلَ وَجْهِهِ فَلَا يَتَنَخَّمَنَّ أَحَدٌ قِبَلَ وَجْهِهِ فِي الصَّلَاةِ
مسند امام احمد بن حنبل · Hadith 5408
It was narrated from ibn Umar that the Prophet (PBUH) said: some sputum in the qiblah of the mosque when he was praying in front of the people. He scratched it then he said when he had finished the prayer: "When one of you is praying, Allah (PBUH) is front of him, so no one should spit to the front whilst praying."
Sanad
حَدَّثَنَا أَبُو سَلَمَةَ أَخْبَرَنَا لَيْثٌ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ