Where should a woman following her husband or another man in prayer stand?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
If a single woman prays with a man—whether she is his wife or a non-mahram (Ajnabiyyah)—the Sunnah is for her to stand behind the Imam and be shielded by him. If the Imam is leading both a man and a woman, the man should stand to the Imam's right, and the woman should stand behind the male follower (Muqtadi). In this way, she is shielded from the Imam by the male follower and remains at a distance from the follower and his line of sight. And Allah the Exalted knows best.
What is the ruling on a woman who learns of her divorce or her husband's death after her *ʿiddah* has ended? And does the *ʿiddah* of a woman who abandoned mourning (*iḥdād*) for the whole period of the *ʿiddah*, or part of it, still end, even though she knew that abandoning it is forbidden?**
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
The waiting period of a widow who is not pregnant is four months and ten days, based on the saying of Allah Almighty (which means): “And those of you who die and leave wives behind, they shall wait concerning themselves for four months and ten days” [al-Baqarah/234]. If she is pregnant, her ʿiddah ends with the delivery of her child. The ʿiddah is calculated by lunar months and begins from the date of death.
If her ʿiddah ends before she learns of her husband’s death, or of his divorcing her, she does not observe the ʿiddah upon learning of it, because her ʿiddah has already ended.
It is stated in al-Bayān fī Madhhab al-Imām al-Shāfiʿī (Vol.11/p.41), one of the books of the Shāfiʿī school: “If a man divorces his wife, or dies while he is absent from her, her ʿiddah is from the time of the divorce or from the time of death. If she does not know of the divorce or the death until her ʿiddah period has ended, then her ʿiddah has ended. If she learns of it before the end of the ʿiddah period, she completes her ʿiddah counting from the time of the divorce or death.”
As for a woman who abandoned mourning throughout the ʿiddah while knowing that it is forbidden, she is sinful, although her ʿiddah has nonetheless ended. And Allah Almighty knows best.
Is it permissible for a woman to shake hands with her brother-in-law?
It is forbidden for the woman to shake hands with her brother-in-law because he isn`t a Mahram (unmarriageable) of hers.
What is the ruling on performing the standing (qiyām) and bowing (rukū‘) portions of the prayer normally, while performing the prostration (sujūd) seated due to knee pain?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
If performing sujūd (prostration) in prayer causes the worshipper pain in the knees, then it is permissible for him to perform it through gesture (īmā') while seated, since Allah, Glorified and Exalted is He, has lifted hardship from His servants. On the authority of ‘Imrān ibn Ḥuṣayn (raḍiyallāhu ‘anh), he said: "I suffered from hemorrhoids, so I asked the Prophet ﷺ about [how to perform] the prayer, and he said: 'Pray standing; if you are unable, then sitting; and if you are unable, then on your side.'" [Ṣaḥīḥ al-Bukhārī]
If the valid excuse later subsides, the worshipper is then obligated to perform the prayer with all its pillars and conditions fully observed — including standing, rukū‘ (bowing), and sujūd (prostration). And Allah, the Exalted, knows best.