(12) باب مَا يَجُوزُ مِنَ الْبُصَاقِ وَالنَّفْخِ فِي الصَّلاَةِ
Narrated Anas:
The Prophet (ﷺ) said, "Whenever anyone of you is in prayer, he is speaking in private to his Lord and so he should neither spit in front of him nor on his right side but to his left side under his left foot."
Reference: Sahih al-Bukhari 1214
In-book reference: Book 21, Hadith 18
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 22, Hadith 305