Is it permissible to purchase the Udhiyah on installments?
It is permissible to purchase the sacrificial animal (uḍḥiyyah) on installments or by borrowing its price. However, it is not recommended for the poor to do so, because they are not required to offer a sacrifice, and Allah does not burden a soul beyond its capacity. If doing so would lead to negligence in providing for one's dependents (nafaqah wājibah), then giving precedence to obligatory maintenance over borrowing to buy the sacrifice is appropriate. This is based on the saying of the Prophet (peace and blessings be upon him): "It is sufficient sin for a person to withhold food from those whom he is responsible to support."
Furthermore, the sacrifice is valid from one who has a debt, but it is preferable (awlā) to repay the debt first, especially if the debt is due immediately (ḥāll). And Allah Almighty knows best.
What is the ruling on eating from one`s Udhiyah?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Sacrifices (Udhiyah) are categorized into two types: the Vowed Sacrifice (Al-Mandhurah) and the Voluntary Sacrifice (Al-Tatawwu').
1. The Vowed Sacrifice (Al-Mandhurah)
The vowed sacrifice is obligatory due to the person’s specific oath. It is not permissible for the person offering the sacrifice, nor for those they are legally responsible for financially supporting (dependents), to consume any part of its meat or fat. Furthermore, it is not permissible to benefit from its hide, hair, or any other part.
If they do consume any part of it, they are required to give in charity an equivalent amount of meat or its market value [Tuhfat al-Muhtaj, by Ibn Hajar al-Haytami (9/364)].
2. The Voluntary Sacrifice (Al-Tatawwu’)
Regarding the voluntary sacrifice, it is permissible for the one offering it to eat from its meat, distribute it as gifts to the wealthy, and give it as charity to the poor.
The Obligatory Portion: It is mandatory to give at least a small portion of it in charity to the poor; this portion should not be less than approximately half a kilogram of raw meat. And Allah the Almighty knows best.
What is the ruling on wiping the head during ablution from behind a barrier like a headscarf (hijab)?
The obligation in ablution is to wipe some of the head; it is not a condition to wipe all of it. As for one who has a turban or headscarf on their head, it is permissible for them to wipe over it after wiping a part of their head in any place. This is easily done at the front of the head. This means the woman begins by wiping the front of her head from under the headscarf, then completes the wiping to the back of the head from over the headscarf. If the woman wipes over the headscarf on her head and the moisture reaches the scalp or some hair within the boundaries of the head, it suffices for wiping the head. And Allah the Almighty knows best.
What is the ruling on ablution without istinja' after sleep?
The sleep of one whose buttocks are not firmly seated on the ground invalidates ablution. Whoever wakes up and wants to pray must perform ablution only. Istinja' is not a condition for the validity of ablution, because it is for removing impurity from the private part. If there is no impurity on the private part, then istinja' is neither obligatory nor recommended. And Allah the Almighty knows best.