What is the ruling on fasting the six days of Shawwal?
Fasting the six days of Shawwal is Sunnah. The Prophet ﷺ said: "Whoever fasts Ramadan and then follows it with six days of Shawwal, it is as if they have fasted for a lifetime." [Narrated by Muslim]
This is because fasting one month of Ramadan is rewarded as fasting for ten months, and the six days are equivalent to sixty days, completing a full year of fasting.
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.
Is it permissible to offer mandatory prayer while sitting?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions. Standing up is a pillar in the mandatory prayer and the prayer is not valid without it unless one cannot do it. As for Nafila (supererogatory prayer), one can perform it in the state of sitting even if he/she can stand, but his/her reward is half the reward of the person who prays while standing if he/sh has no legal excuse for such an act. And Allah Knows Best.
What is the ruling of Islamic Law on selling gold or silver in installments or for a differed price?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is prohibited (haram) to sell gold or silver in installments or for a deferred price; rather, immediate hand-to-hand exchange (Taqabud) is mandatory, otherwise, it is considered usury (Riba). The Messenger of Allah ﷺ said: 'Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt—like for like, hand to hand. Whoever increases or asks for an increase has engaged in Riba; the receiver and the giver are the same in this regard.' (Narrated by Muslim). Furthermore, when exchanging new gold for used gold, they must be of equal weight, or it falls into Riba.
The permissible solution (al-makhraj) is for the merchant to purchase the used gold for cash first, and then sell the new gold for cash in a separate transaction. However, the price must be paid during the sitting of the contract (Majlis al-Aqd) for both deals. Alternatively, the jeweler may take the used gold with the intent of remodeling or repairing it, and then charge a fee for the craftsmanship or repair work. And Allah the Exalted knows best."