What is the ruling on swallowing saliva while fasting?
It is permissible for a fasting person to swallow their saliva because avoiding it would cause undue hardship and excessive strictness in religion. Islam discourages such excessiveness since Allah the Almighty intends ease for His followers and does not intend to put them in hardship.
Does the fast become invalid if water from rinsing the mouth reaches the stomach while performing ablution?
If water reaches the stomach without the fasting person exceeding normal rinsing or being excessive, their fast remains valid.
However, if they exceed the normal practice or exaggerate in rinsing, causing water to enter the stomach, their fast is invalid.
This is because excessiveness in rinsing is prohibited for a fasting person, as the Prophetﷺ said: "Exaggerate inhaling water during ablution, except when you are fasting." [Narrated by the Four Imams]
Transgression (Ta‘addi) refers to rinsing the mouth more than three times, while exaggeration (Mubalaghah) includes gargling, drawing water deep into the nasal passages, or filling the mouth with water in an unusual manner.
What is the ruling of Islamic Law on applying perfume before entering the state of ihram
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Applying some perfume (ṭīb) before entering the state of iḥrām does not affect the validity of the Ihram, even if its trace remains after the iḥrām has begun. Indeed, it is sunnah for the pilgrim performing Ḥajj or ʿUmrah to perfume himself before iḥrām.
The scholar Nawawī al-Jāwī (may Allah have mercy on him) said: “The third of them is applying perfume to the body shortly before it, that is, before iḥrām, whether the one entering iḥrām is male or otherwise, young or old, married or unmarried. The recommendation applies after performing the ritual bath (ghusl), and it is fulfilled with any perfume whatsoever, though the best is musk, mixed with rose water or the like. There is no objection to the perfume remaining on the body after iḥrām; however, if a woman becomes bound by the mourning observance (iḥdād) after entering iḥrām, she must remove it. As for perfuming the garment, it is merely permissible, not recommended, according to the reliable position (al-muʿtamad). But if one removes his perfumed garment while the scent is still present in it and then wears it again, he is liable for the fidyah (expiation).” [Nihāyat al-Zayn, Vol.1/212]. And Allah Almighty knows best.
Is it permissible for someone who is unable to fast to pay the fidyah (ransom/compensation payment) to himself, due to his own poverty?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
It is not permissible, nor does it fulfill the obligation, for a sick person who is currently and permanently unable to fast to pay the fidyah (ransom/compensation payment) to himself, since it is a financial obligation owed by him, established as a standing debt upon him — much like any other debt he owes. If he were to pay it to himself, it would not thereby be discharged. So if he cannot find [anyone eligible to] pay it to, it remains a standing obligation upon him, and is not thereby waived. If Allah, the Mighty and Majestic, later grants him wealth, it becomes obligatory upon him to pay it out to the poor and needy.
Imam al-Khaṭīb ash-Shirbīnī (raḥimahullāh) said: "There is no difference in the obligation of the fidyah between the wealthy and the poor person; its benefit lies in its remaining established as a standing debt upon the poor person [until he is able to pay it] — and this is the more correct position (al-aṣaḥḥ), as indicated by the wording of ar-Rawḍah and its source text." [Mughnī al-Muḥtāj, Vol.2/P.174]
Accordingly: it is not permissible for a Muslim to pay the fidyah to himself while he remains poor. If the sick person is poor, he is not obligated to pay the fidyah immediately, and it remains a standing debt upon him until a time when he has sufficient means and wealth. And Allah, the Exalted, knows best.