What is the ruling on one who wiped over his leather socks (*khuff*) while resident and then traveled, or wiped while traveling and then became resident? And likewise, what is the ruling on one who incurred a minor ritual impurity (*ḥadath aṣghar*) while resident, then traveled and wiped while traveling?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Whoever wipes over his leather socks (khuffayn) while resident and then travels, or wipes while traveling and then becomes resident, before a day and a night have passed in both cases, completes the wiping period of a resident. If he wipes while resident and then travels after a day and a night have passed, he must remove the socks, because the period has ended. Likewise, if he wipes while traveling and then becomes resident after a day and a night have passed, he must remove them as well.
Whoever breaks his wuḍūʾ while resident and then wipes while traveling takes the ruling of a traveler as regards the duration of wiping, so long as he does not become resident. It is stated in ʿUmdat al-Sālik wa ʿUddat al-Nāsik (Vol.1/p.15): “If he wipes over both [socks] or one of them while resident and then travels, or wipes while traveling and then becomes resident, or doubts whether he began the wiping while traveling or while resident, he completes only the wiping period of a resident. But if he broke his wuḍūʾ while resident and wiped while traveling, he completes the period of a traveler, whether or not the full time of a prayer had passed over him while resident.” And Allah Almighty knows best.
What is the ruling on forgetting an integral of the prayer?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Whoever forgets an integral (Rukn) of the prayer and remembers it before reaching the equivalent point in the subsequent unit (Rak'ah), must return to it (i.e., perform it) and complete his prayer, then perform the prostration of forgetfulness (Sujud al-Sahw) at the end of his prayer. However, if he remembers it after reaching the equivalent point in the subsequent unit, the Rak'ah in which the integral was forgotten is invalidated, and the current unit takes its place; he then completes a full Rak'ah to compensate and performs the prostration of forgetfulness.
It is stated in Nihayat al-Muhtaj ila Sharh al-Minhaj (Vol.1/P.543): 'If he becomes certain at the end of his prayer, or after the Salam—provided the interval is not long according to custom and he has not stepped on an impurity—that he omitted a prostration from the final Rak'ah, he must perform it and repeat the Tashahhud, as his previous Tashahhud occurred before its proper place. If the omission was from a Rak'ah other than the final one, he must perform a full Rak'ah, because the deficient unit was completed by a prostration from the subsequent one, rendering the rest of that subsequent unit void.' And Allah the Exalted knows best.
What is the ruling on performing ablution (wudu') and ritual bathing (ghusl) with Zamzam water?
It is permissible to perform ablution and ritual bathing with Zamzam water. However, scholars disliked using it for cleaning after relieving oneself (istinja'). And Allah the Almighty knows best.
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.
