Does collecting saliva and swallowing it break the fast?
Swallowing collected saliva does not break the fast, but it is an unnecessary and meaningless act.
What is the ruling on someone who fainted while fasting?
● If a person had the intention to fast from the night but then fainted during the day and regained consciousness before sunset, even for a moment, their fast remains valid.
● However, if they remain unconscious for the entire day, from Fajr until sunset, their fast does not count, and they must make up for that day later.
Is prayer nullified by nose bleed?
All praise be to Allah, The Lord of The Worlds. Blood coming out of the nose, or a wound doesn`t nullify prayer regardless of its quantity. And Allah Knows Best.
Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.