What is the ruling on swearing on the Holy Quran and breaking that oath?
It is impermissible to swear on the Holy Quran in vain, and it is also impermissible to subject it to such an act since breaking the oath after swearing on the Quran entails an expiation.
What is the ruling on forgiving a tenant next month's rent, with the intention of counting it toward zakāh al-māl?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
It does not fulfill the obligation to count the rent owed on a house, or a portion of it, in lieu of zakāh. Rather, it is necessary to first transfer ownership of the zakāh amount to the poor person directly; only afterward may he be asked to pay the rent [from that money].
It is stated in ‘Umdat as-Sālik (p. 112): "If someone gives [money] to a poor person, stipulating that the recipient return it to him in payment of a debt owed to him, or says, 'I am making what you owe me into zakāh, so take it [as such]' — this is not valid. But if he gives it to him with the [unstated] intention that the recipient will use it to repay him, or says, 'Repay what you owe me, so that I may [then separately] give it to you as zakāh,' or the debtor himself says, 'Give it to me, so that I may [then] repay you with it' — this is valid, and there is no binding obligation for the recipient to actually fulfill this [informal understanding]."
We would also remind [the reader] of the ḥadīth of the Prophet ﷺ: "The Muslim is the brother of the Muslim: he does not wrong him, nor does he abandon him [to harm]. Whoever attends to the needs of his brother, Allah, the Mighty and Majestic, will attend to his needs. Whoever relieves a Muslim of a hardship, Allah, the Mighty and Majestic, will relieve him of one of the hardships of the Day of Resurrection. And whoever conceals [the faults of] a Muslim, Allah will conceal him on the Day of Resurrection." (Agreed upon). And Allah, the Exalted, knows best.
Is it permissible to consume the meat of a sacrifice (Dhabihah) offered as an act of devotion to Allah, seeking His protection for my family?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is permissible to eat from this sacrifice, and the reward [for it] is according to what is given to the poor. And Allah the Exalted knows best.
What is the ruling on water that contains ornamental fish — does it become impure on account of their waste?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
The water in a pond containing ornamental fish is pure so long as it has not been altered, for a small amount of fish waste (rawth) is pardoned and overlooked — provided it does not change the water.
It is stated in Ḥāshiyat al-Jamal ʿalā Sharḥ al-Manhaj (Vol.1/P.178): "A small amount of hair from a non-edible animal is pardoned, as is a small amount of hair from a riding animal — on account of the hardship involved in avoiding it — and likewise a small amount of fish waste is pardoned, unless it alters the water." And Allah the Almighty knows best.