What is the meaning of the Prophetic statement that a boy is held in pledge (murtahan) for his 'aqīqah?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The first interpretation: That if the boy dies in infancy without an 'aqīqah having been performed on his behalf, he will not intercede for his parents on the Day of Resurrection. This is the position of Imam Aḥmad ibn Ḥanbal, and Imam al-Khaṭṭābī concurred with him, stating: "The finest of what has been said regarding this matter is the position adopted by Aḥmad ibn Ḥanbal." — [Fatḥ al-Bārī by Ibn Ḥajar,{Vol.9/P.594]
The second interpretation: That the child is likened to a pledged object (marhūn) — one from which full benefit and enjoyment cannot be derived until it is redeemed. A blessing is only made complete upon the one blessed when they fulfil the obligation of gratitude (shukr), and the prescribed expression of gratitude for this particular blessing is what the Prophet ﷺ established as Sunnah — namely, the slaughtering of the 'aqīqah on behalf of the newborn as an act of thankfulness to Allah the Almighty and as a supplication for the wellbeing and safety of the child. This is the position of Mullā 'Alī al-Qārī. See: [Mirqāt al-Mafātīḥ Sharḥ Mishkāt al-Maṣābīḥ, Vol.7/P.2688]
And Allah Almighty knows best.
What is the ruling of Islamic Law on performing prayer on the upper floors of al-Masjid al-Ḥarām?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Facing the actual structure of the Ka‘bah (‘ayn al-Ka‘bah) is one of the conditions for the validity of the prayer. The scholars have clarified what is meant by "the actual structure of the Ka‘bah."
Imam ash-Sharwānī (raḥimahullāh) said: "What is meant by its ‘ayn (actual structure) is its physical body, or the airspace directly aligned with it — if the person praying is not inside it. But if he is inside it, then the airspace alone does not suffice; rather, the actual physical structure must be faced, such that even if he faces a projecting part of it measuring roughly two-thirds of a dhirā‘ (cubit) or more, this would be sufficient." [Ḥāshiyat ash-Sharwānī ‘alā Tuḥfat al-Muḥtāj, Vol.1/P.484]
Sheikh al-Qulyūbī (raḥimahullāh) said: "Unlike one who prays outside it — i.e., outside the Ka‘bah — for him the airspace (directly above it) suffices, even if he is higher than it, or even if he is at the location where it (hypothetically) has been demolished." [Ḥāshiyat al-Qulyūbī ‘alā Sharḥ al-Minhāj, Vol.1/P.154]
Accordingly, the prayer is valid on the upper floors of al-Masjid al-Ḥarām, even though these floors are higher than the roof of the Ka‘bah itself. And Allah, the Exalted, knows best.
Is it obligatory to have an intention (niyyah) for every prayer?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is obligatory for the worshiper to have a specific intention (Niyyah) for every prayer, meaning they must consciously intend the act of worship they are performing. The intention is a pillar (Rukn) of the prayer, and the prayer is not valid without it. It is not a requirement to utter the intention verbally; rather, doing so is considered a recommended Sunnah. And Allah the Exalted knows best.
Is it permissible to give Zakah (obligatory charity) to one`s poor sister, or brother?
It is permissible for one to give the Zakah to his poor sister, or brother if providing for them isn`t due on him, and the sister doesn`t receive sufficient provision from whomever that is due on. And Allah Knows Best.