How is night prayer offered?
Night prayer is offering voluntary prayer after Maghrib and before Fajr (Dawn). As for Tahajjud, it is offering voluntary prayer at night after waking up voluntarily, and for Allah`s sake as He Says (What means): "And pray in the small watches of the morning: (it would be) an additional prayer (or spiritual profit) for thee: soon will thy Lord raise thee to a Station of Praise and Glory!" [Al-Isra`/79]. Offering Tahajjud is better than offering voluntary prayer before going to bed.
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.
Is it permissible for a pious Muslim woman to stay with her husband who had quit praying out of laziness?
Quitting prayer is one of the major grave sins that come after disbelieving in Allah, but the wife of such a person isn`t considered divorced, rather, she should exert all her efforts in order to bring him back to the way of Islam. However, if his sin is likely to lure her from the way of Islam, then she had better separate from him by lawful means such as Mokhal`aa (When a wife pays a compensation for her husband in return for divorcing her). Moreover, if she exercises patience, and remains steadfast on her faith, then there is no harm in doing that.
Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.