What is the semi-circular structure attached to the Holy Kabah?
The semi-circular structure attached to the Holy Kabah is Hijr Al-Kabah (is a low wall originally part of the Kabah) and passing behind it is an obligation while making Tawaf because it is a part of the Holy Kabah. And Allah Knows Best.
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.
What is the Islamic ruling on the aqiqa?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The 'aqīqah is a confirmed Sunnah (sunnah mu'akkadah). Two sheep are to be slaughtered for a newborn boy, and one sheep for a newborn girl. This is established by numerous Prophetic traditions, among them:
The narration of Samurah ibn Jundub, may Allah be pleased with him, who reported that the Messenger of Allah ﷺ said: "Every child is held in pledge for his 'aqīqah, which is slaughtered on his behalf on the seventh day, and he is named, and his head is shaved." — Narrated by al-Tirmidhī, who graded it as ḥasan ṣaḥīḥ.
And the narration of 'Ā'ishah, may Allah be pleased with her, who said: "The Messenger of Allah ﷺ commanded us to slaughter one sheep as 'aqīqah for a girl, and two sheep for a boy." — Narrated by Aḥmad and Ibn Mājah.
The imperative in these narrations is understood to denote recommendation rather than obligation, based on the ḥadīth of 'Amr ibn Shu'ayb, on the authority of his father, on the authority of his grandfather, who said: The Messenger of Allah ﷺ was asked about the 'aqīqah, whereupon he said: "Allah does not love 'uqūq" — as though he disliked the name itself — and then said: "Whoever has a child born to him and wishes to offer a sacrifice on their behalf, let them do so: two equivalent sheep for a boy, and one sheep for a girl." — Narrated by Aḥmad and Abū Dāwūd.
The legal inference drawn from this narration is that the Prophet ﷺ linked the slaughter to the wish and willingness of the individual, saying: "whoever wishes to offer a sacrifice... let them do so" — thereby indicating that the 'aqīqah is recommended (mustaḥabb) and not obligatory (wājib).
And Allah Almighty knows best.
What is incumbent upon the one offering the sacrifice if, after slaughtering the animal, they discover that one of its internal organs is damaged or diseased?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The presence of disease or defect in the internal organs of a sheep does not affect the validity of the sacrificial animal, unless the disease leads to the animal becoming emaciated and its meat becoming corrupted.
It is stated in al-Iqnā' (2/590) by Imam al-Shirbīnī: "The third disqualifying condition: an animal with a manifest illness — meaning one whose illness visibly results in emaciation and corruption of its meat. However, if the illness is minor and does not produce such effects, it doesn`t affect the validity of the sacrificed animal." And Allah Almighty knows best.
