Does using a respiratory device (oxygen) affect the validity of fasting?
Using an oxygen device does not affect the validity of fasting because oxygen is a gas with no physical substance.
However, if medicinal substances with physical particles are added to the oxygen, its use would break the fast, as it enters the body cavity through a natural passage.
Which is more excellent for a woman: to pray in the mosque or in her house?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Our Master the Prophet ﷺ said: 'It is more excellent for a woman to pray in her house than in her courtyard, and more excellent for her to pray in her private chamber than in her house.' Therefore, a woman’s adherence to her home and her refraining from going to the mosques—in obedience to the command of Allah the Exalted—attains a great reward and abundant recompense. Furthermore, women praying in congregation within their homes is better than their attendance at the mosques, based on the aforementioned Hadith. And Allah the Exalted knows best.
Is it permissible for an elderly person, a pregnant woman, or someone with a chronic illness to pay fidyah before Ramadan begins?
It is not permissible for an elderly person, a pregnant woman, or someone with a chronic illness to pay fidyah before Ramadan begins.
Additionally, it is not allowed to pay fidyah for more than one day in advance, because fidyah is a substitute for fasting, and fasting is not yet obligatory at that time.
However, it is permissible to pay fidyah for a single day in advance, by analogy with paying zakat up to one year in advance.
What is the ruling of Islamic Law on a father shaking hands with his son’s wife after she has been divorced three times?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
The wife of one’s son is among the women permanently prohibited to the husband’s father as soon as the marriage contract is concluded, based on the saying of Allah the Exalted: “Prohibited to you are your mothers, your daughters, your sisters, your paternal aunts, your maternal aunts, your brother’s daughters, your sister’s daughters, your foster mothers, your foster sisters, your wives’ mothers, and your stepdaughters under your guardianship [born] of your wives with whom you have consummated marriage. But if you have not consummated marriage with them, there is no sin upon you. [Also prohibited are] the wives of your sons who are from your loins, and that you take [in marriage] two sisters simultaneously, except for what has already occurred. Indeed, Allah is ever Forgiving and Merciful.” [al-Nisāʾ/23]
This prohibition begins once the son’s marriage contract with his wife is complete, and it remains in force even if the son separates from her before consummation or before any seclusion (khalwah) with her. It is therefore permissible for the father to shake her hand and to be alone with her, provided there is no fitnah (temptation) and no suspicion.
It is stated in ʿUmdat al-Sālik (p. 204): “It is forbidden to marry… the wives of one’s fathers and of one’s sons. All of these women become prohibited by the mere contract, … all of that being a permanent prohibition.” End quote, with slight adaptation. And Allah Almighty knows best.