the saliva carries along, and they swallow it, their prayer does not become invalid; because it is impossible to avoid this. If one keeps a morsel in their mouth and does not swallow it, it is disliked; because it distracts them from the humility of the prayer, the remembrance, and the recitation within it, but it does not invalidate it; because it is a minor action, so it resembles the case where one holds something in their hand. And Allah knows best.
الرِّيقُ، فابْتَلَعَه، لم تَفْسُدْ صلاتُه؛ لأنَّه لا يُمْكِنُ الاحْتِرَازُ منه. وإن تَرَكَ في فِيهِ لُقْمةً ولم يَبْتَلِعْها، كُرِهَ؛ لأنَّه يَشْغَلُه عن خُشُوعِ الصَّلاةِ والذِّكْرِ والقِرَاءَةِ فيها، ولا يُبْطِلُها؛ لأنَّه عَمَلٌ يَسِيرٌ، فأَشْبَهَ ما لو أمْسَكَ شيئًا في يَدِه. واللهُ أعلمُ.