Sahih Muslim 551
Sahih Muslim · Book 5: The Book of Mosques and Places of Prayer · The prohibition of spitting in the masjid, during prayer and at other times. The prohibition of a praying person spitting in front of him or to his right
Anas b. Malik reported:
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى ، وَابْنُ، بَشَّارٍ قَالَ ابْنُ الْمُثَنَّى حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ ، حَدَّثَنَا شُعْبَةُ ، قَالَ سَمِعْتُ قَتَادَةَ ، يُحَدِّثُ عَنْ أَنَسِ بْنِ مَالِكٍ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا كَانَ أَحَدُكُمْ فِي الصَّلاَةِ فَإِنَّهُ يُنَاجِي رَبَّهُ فَلاَ يَبْزُقَنَّ بَيْنَ يَدَيْهِ وَلاَ عَنْ يَمِينِهِ وَلَكِنْ عَنْ شِمَالِهِ تَحْتَ قَدَمِهِ " .
The Messenger of Allah (ﷺ) said: When any one of you is engaged in prayer, he is holding intimate conversation with his Lord, so none of you must spit in front of him, or towards his right side, but towards his left side under his foot.