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.
Is the son of the sister by breastfeeding considered a mahram in Islam, and is it permissible for a woman to go for Hajj with him?
Everything that is prohibited by lineage is also prohibited by breastfeeding. The son of the sister by breastfeeding is considered a mahram, just like the son of the sister by blood, and it is permissible for him to be her mahram for Hajj and Umrah. And Allah Knows Best.
What are the conditions for a valid Udhiyah?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
First: The age of the animal must meet the Sharia requirements. These requirements vary depending on the type of sacrifice:
Camels: Must have completed five years and entered their sixth.
Cows: Must have completed two years and entered their third.
Goats: Must have completed two years and entered their third. As for Sheep, they must have completed one year and entered their second.
Some scholars have permitted goats that have completed one year and entered their second.
The Hanafi school, along with an opinion in the Maliki school, permits sacrificing sheep that are at least six months old, provided they are healthy and physically substantial. According to the Shafi’i school, it is permissible if the sheep sheds its front teeth (ajdha') before reaching one year [Al-Iqna’, by Al-Shirbini (Vol.2/P.588)].
Second: Soundness and freedom from defects. The animal must be free from any defect that causes a decrease in its meat or market value. This is based on the hadith narrated by Al-Bara' bin 'Azib, that the Prophet (peace be upon him) said:
"Four [defects] are not permissible in sacrifices: A one-eyed animal whose blindness is evident, a sick animal whose illness is evident, a lame animal whose lameness is evident, and an emaciated animal that has no marrow in its bones." [Reported by Abu Dawood and Al-Tirmidhi, who graded it as authentic].
These defects are detailed as follows:
Evident Lameness: It is not permissible to sacrifice a lame animal if the lameness is severe enough to prevent it from walking to the pasture or seeking food, as this leads to a decrease in its meat. However, slight lameness that does not hinder its grazing is overlooked.
Evident Blindness (One-eyed): It is not permissible to sacrifice a sheep, cow, or camel that has a white film over its eye blocking light, or one that has lost an eye entirely. Weak vision that does not affect its ability to eat does not prevent the sacrifice from being valid.
Evident Illness: An animal with a clear sickness that prevents it from eating or moving is not valid. This includes severe mange (Jarab) that spoils the meat.
Extreme Emaciation: An animal so thin that there is no marrow left in its bones is invalid. The standard for emaciation that invalidates the sacrifice is that which spoils the quality of the meat to the point that people would find it undesirable even in times of plenty.
Additional Considerations:
These are the defects mentioned in the Prophetic tradition, and any defect that causes emaciation or reduces the meat or value is compared to them by analogy. This includes animals that are mentally unstable (diseased), those with mange, or those with a missing ear. In contrast, a slit or pierced ear does not affect the validity of the sacrifice. And Allah the Almighty knows best.
Where should a woman who is led by her husband in prayer stand?
All perfect praise be to Allah The Lord of The Worlds It is from Sunnah (Prophetic tradition) that she stands behind him. And Allah Knows Best.