Who is the one required to slaughter the 'aqīqah?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
It is Sunnah for the 'aqīqah to be slaughtered by the guardian of the newborn — the one upon whom the child's financial maintenance is obligatory — provided he is financially capable of doing so. 'Alī ibn Abī Ṭālib, may Allah be pleased with him, reported: "The Messenger of Allah ﷺ performed the 'aqīqah for al-Ḥasan with one sheep." — Narrated by al-Tirmidhī. And Allah Almighty 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.
Is the marriage, which lacks a valid legal contract, a guardian, and a court registration, valid?
It is incumbent that a valid marriage contract be concluded in the presence of a guardian and two trustful witnesses, and it should be registered in the court to protect the rights of the wife. Actually, a valid marriage contract is what differentiates between sound marriage and fornication.
What is the wisdom behind legislating the Udhiyah?
The Muslim must know that through the Uḍḥiyah, he complies with the command of Allah, the Exalted, and performs a worship that brings him closer to Allah and distances him from the Fire.
The Uḍḥiyah holds profound wisdoms and noble meanings, including:
1-Reviving the Sunnah of Abraham, peace be upon him: He complied with Allah's command when He ordered him to slaughter his son Ishmael. Abraham, peace be upon him, succeeded in the test, and when he was about to slaughter his son, Allah sent down a ram to ransom Ishmael and commanded him to slaughter it instead. Allah, the Exalted, says {what means]: "And when he reached with him [the age of] exertion, he said, 'O my son, indeed I have seen in a dream that I [must] sacrifice you, so see what you think.' He said, 'O my father, do as you are commanded. You will find me, if Allah wills, of the steadfast.' And when they had both submitted and he put him down upon his forehead, We called to him, 'O Abraham, You have fulfilled the vision.' Indeed, We thus reward the doers of good. Indeed, this was the clear trial. And We ransomed him with a great sacrifice." [Al-Ṣāffāt/102-107]. Thus, the sacrificial offering became an enduring Sunnah until the Day of Judgment, and Muslims offer their wealth as sacrifices, drawing closer to Allah, the Exalted, reviving this great Sunnah.
2-Providing abundance for people on Eid day and the Days of Tashrīq: Among the wisdoms of the Uḍḥiyah is that the Muslim provides generously for his family, neighbors, relatives, and the poor during these days. The Muslim is encouraged to eat from his sacrifice, give charity from it to the poor, and gift from it to his wealthy neighbors. Thus, goodness spreads throughout the entire community. The Prophet, peace and blessings be upon him, said: "The Days of Tashrīq are days of eating and drinking." (Narrated by Muslim). Allah, the Exalted, says {what means}: "And the camels and cattle We have appointed for you as among the symbols of Allah; for you therein is good." [Al-Ḥajj/36]. This good includes the good of both this world and the Hereafter.
