What is the ruling on praying in congregation at the mosque?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Congregational prayer (Salat al-Jama‘ah) is a communal obligation (Fard Kifayah) for resident men regarding the performance of the prescribed (obligatory) prayers. For men, praying in congregation at the mosque is better than praying elsewhere, such as at home. On the authority of Abdullah bin Umar, the Messenger of Allah ﷺ said: 'Prayer in congregation is twenty-seven degrees more excellent than the prayer of a person alone' (Reported by Bukhari & Muslim). Furthermore, on the authority of Abu Hurayrah, the Messenger of Allah ﷺ said: 'Shall I not tell you that by which Allah erases sins and raises ranks?' They said, 'Of course, O Messenger of Allah.' He said: 'Performing wudu thoroughly despite difficulties, taking many steps toward the mosques, and waiting for the next prayer after the prayer; that is your Ribat (steadfastness)' (Narrated by Muslim).
As for a woman, her praying in congregation at home is better for her than in the mosque, according to the saying of our Master the Prophet ﷺ: 'Do not prevent your women from attending the mosques, but their homes are better for them' (Narrated by Abu Dawood). Young boys should be encouraged to attend the mosques and congregational prayers so they may become accustomed to them. And Allah the Exalted knows best.
What is the ruling on one who doubts washing a limb before or after finishing ablution?
If a person performing ablution doubts leaving the washing of a limb from the limbs of ablution during his ablution, he must repeat washing that limb and wash what comes after it. If he doubts leaving the washing of a limb after finishing the ablution, there is nothing upon him. And Allah the Almighty knows best.
I bought an apartment, and I am saving money to pay the remaining balance of its price — is zakāh obligatory on this money?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Zakāh is obligatory on all saved/hoarded wealth. Once the total wealth reaches the niṣāb (minimum threshold liable for zakah— equivalent to the value of 85 grams of pure 24-karat gold) and a full ḥawl (lunar year) has elapsed over it, zakāh becomes obligatory at a rate of (2.5%) — even if the wealth is earmarked for basic future needs, and even if the wealth's owner is in debt. Debt does not prevent the obligation of zakāh, nor is it deducted when calculating the zakāh due, based on the general and unrestricted wording of all the Qur'anic verses commanding zakāh, which draw no distinction between someone in debt and anyone else.
It is stated in ‘Umdat as-Sālik, from the books of the Shāfi‘ī school: "If someone possesses exactly the niṣāb, and owes an equivalent amount in debt, zakāh remains obligatory on what is in his possession, and the debt does not prevent this obligation" — meaning, the obligation of zakāh on what is presently in his possession.
The ḥawl (annual cycle) recognized for zakāh, as well as for the other sharī‘ah obligations that Allah, the Exalted, has imposed upon Muslims, is the Hijrī (lunar) year. And Allah, the Exalted, knows best.
What is the ruling on someone who possesses gold with the intention of saving/hoarding it, and owns nothing else — is he obligated to sell a portion of it in order to pay the zakāh due on it?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Zakāh becomes immediately obligatory on cash, and likewise on gold — that which is not designated for a woman's personal adornment— once both reach the niṣāb (minimum threshold liable for zakah) and a full ḥawl (lunar year) has passed over them. It is not permissible to delay payment when it is genuinely possible to pay — meaning, when the wealth and the eligible recipients are both available. It is stated in Mughnī al-Muḥtāj (Vol.2/p.129): "Zakāh is obligatory immediately once it becomes feasible to pay it, meaning when the wealth and the eligible recipients are both present."
The one paying zakāh must discharge the obligatory zakāh due on saved (hoarded) gold either from the gold itself, or from its equivalent monetary value, in the event that no other funds are available — since paying from the gold itself is the original default (al-aṣl). It becomes permissible to pay from other funds instead only because zakāh is built upon the principle of ease and leniency, as stated in Asnā al-Maṭālib (Vol.1/p.366): "When a full ḥawl has elapsed on wealth other than trade goods... zakāh attaches to the actual asset itself (al-‘ayn), and the poor effectively become partners in it — even, for example, [becoming partners] in camels through the value of a sheep [owed as zakāh on them]... Paying from other wealth is permitted only because zakāh is built upon the principle of ease and leniency."
Accordingly: the one paying zakāh must discharge it either from the actual saved gold itself, or by selling a portion of the gold equal to the amount of zakāh owed. He may also borrow money to pay the zakāh, or pay the zakāh in installments before the ḥawl is complete [as an advance payment]. And Allah, the Exalted, knows best.