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 ablution without istinja' after sleep?
The sleep of one whose buttocks are not firmly seated on the ground invalidates ablution. Whoever wakes up and wants to pray must perform ablution only. Istinja' is not a condition for the validity of ablution, because it is for removing impurity from the private part. If there is no impurity on the private part, then istinja' is neither obligatory nor recommended. And Allah the Almighty knows best.
What is the ruling on congregational prayer performed outside the mosque, and is it a condition that it be performed in a mosque in order to attain the full reward?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
It is not a condition for attaining the reward of congregational prayer that it be performed in a mosque; however, a Muslim should still be keen to perform his prayers in the mosque, so as not to miss out on immense reward. This is due to the virtue of the mosque and of spending time there (i‘tikāf), the typically larger number of worshippers present, and the additional reward gained through walking to and from the mosque. On the authority of Abū Hurayrah (raḍiyallāhu ‘anh), the Messenger of Allah ﷺ said: "Whoever purifies himself in his house, then walks to one of the houses of Allah to fulfill one of the obligations Allah has prescribed, one of his steps will erase a sin, and the other will raise him a degree [in status]." (Related by Muslim)
Whoever misses congregational prayer at the mosque should still strive to pray in congregation at his workplace, or together with the members of his household. And Allah, the Exalted, knows best.
Is it permissible for a woman to sit with her brothers-in-law?
It is impermissible for a woman to sit with her brothers-in-law, and it is also impermissible for a person to have a Khulwa (seclusion) with his sister-in-law.
