What is the ruling on one who vowed not to speak to a certain person, then forgot his vow and spoke to him?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Whoever swears an oath or makes a vow to abstain from something has a choice: if he wishes, he may keep to his vow, or if he wishes, he may offer the expiation of an oath (kaffārat yamīn). The Prophet (peace and blessings be upon him) said: “The expiation for a vow is the expiation for an oath.” Narrated by Muslim. This type of vow is called a nadhr al-lajāj (a vow made in stubbornness or anger).
If a person makes a vow and then forgets it, nothing is due from him, for forgetfulness is among the excuses that lift legal responsibility (taklīf) from a Muslim. This is based on the saying of the Prophet (peace and blessings be upon him): “Actions are judged only by intentions, and every person will have only what he intended.” [Narrated by al-Bukhārī]. There is no intention for the one who forgets or errs. It is also based on the report: “Indeed, Allah has pardoned for my Ummah mistakes, forgetfulness, and what they are compelled to do.” Narrated by Ibn Mājah and others, and graded authentic by Ibn Ḥibbān and al-Ḥākim.
It is stated in ʿUmdat al-Sālik (p. 243), one of the books of the Shāfiʿī school: “Whoever swears, [for example], ‘I will not enter the house,’ and then enters it forgetfully, ignorantly, under compulsion, or being carried, he does not break his oath.” And Allah Almighty knows best.
Is the father a Mahram (Non-marriageable) to his son`s mother-in-law?
The father is a non-Mahram (Marriageable) to his son`s mother-in-law, so it is impermissible for them to look at each other, or to have a seclusion (Khalwah).
What is the ruling on someone who combines two prayers as an early combination (jam‘ taqdīm), and then arrives at his place of residence during the time of the second prayer — is he obligated to repeat it?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Whoever combines Ẓuhr and ‘Aṣr while traveling — that is, before he has reached the built-up boundaries of his hometown [upon returning] — his combination (jam‘) of the two prayers remains valid, even if he arrives at his place of residence before the time for the second prayer has actually begun. This is because the combination was already validly completed with its proper conditions fulfilled, and he is not obligated to repeat the second prayer [upon arrival].
A traveler is permitted to make use of the concessions of shortening (qaṣr) and combining (jam‘) prayers once the distance of travel reaches (81 km) or more, provided that his journey is a permissible one, and that he begins shortening and combining only after actually setting out on the journey and passing beyond the built-up limits of the city in which he resides. And Allah, the Exalted, knows best.
Is Zakat al-Fitr obligatory for an unborn child (fetus)?
Zakat al-Fitr is not obligatory for a fetus. However, if the child is born before sunset on the last day of Ramadan, then Zakat al-Fitr must be given on their behalf.