What is the ruling of Islamic Law regarding one who purchases a sacrificial animal (uḍḥiyah) and it then develops a defect before slaughter?
Praise be to Allah, and peace and blessings upon our master, the Messenger of Allah.
If a defect that invalidates the sacrifice (uḍḥiyah) arises after its purchase — for example, if one purchased a sound, defect-free animal, and it then developed a limp, blindness in one eye, or a similar defect before slaughter — it does not fulfill the requirement of a valid uḍḥiyah, according to the Shāfi'ī school.
It is stated in Asnā al-Maṭālib fī Sharḥ Rawḍ al-Ṭālib (Vol.1/P.535): "Even if the limp develops [in the animal] while the knife is upon it, it still does not fulfill the requirement, because it is lame at the moment of slaughter — this is analogous to a case where a sheep's leg breaks and one hastens to slaughter it [in that condition]."
The Ḥanbalī school, however, held that if the one offering the sacrifice purchased the animal while it was sound and defect-free, and a defect then befell it afterward, the sacrifice remains valid and there is no obligation to replace it.
It is stated in Masā'il al-Imām Aḥmad, one of the Ḥanbalī reference works (Vol.8/P.4021): "I said: If a person purchases the sacrificial animal while it is sound, and it is then afflicted with illness, blindness in one eye, or a broken limb [before slaughter]? He [Imam Aḥmad] said: It is said that it still fulfills the requirement. Isḥāq said likewise, because he purchased it while sound, and the defect befell it only afterward, so it remains sufficient on his behalf." [End of quote]
Accordingly, a sheep afflicted with a defect that invalidates the sacrifice does not fulfill the requirement of a valid uḍḥiyah — whether the defect arose after purchase or during the slaughter itself — according to the Shāfi'ī school. However, there is no objection to following the Ḥanbalī position on this matter [as a valid alternative]. And Allah, the Most High, knows best.
Should the Zakah (obligatory charity) giver tell the poor recipient that this is the Zakah of his money?
No, he shouldn`t. But, the Zakah giver should make an intention in his heart that it is the Zakah of his money when paying it to the poor. And Allah Knows Best.
What is the ruling of Islamic Law on the prayer of zawal?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
It is recommended (sunnah) to pray four rakʿāt — either with a single tasleem or as two separate sets of two rakʿāt — immediately following the sun's decline from its zenith (zawāl). This prayer is distinct from the regular Sunnah prayer of Ẓuhr (sunnat al-ẓuhr al-rātibah), as explicitly stated by the Shāfiʿī jurists.
It is mentioned in Nihāyat al-Muḥtāj: "The prayer of zawāl is offered after the sun's decline — so were one to perform it before that, it would not count. It consists of two or four rakʿāt and is distinct from the Sunnah of Ẓuhr, as is evident from the fact that it is mentioned separately after the regular Sunnah prayers, and it becomes a make-up prayer (qaḍāʾ) if a long period of time passes by customary reckoning... Al-ʿAlqamī stated: 'Scholars refer to this as the Sunnah of Zawāl, and it is distinct from the four rakʿāt that constitute the Sunnah of Ẓuhr.' Our shaykh said: Al-Ḥāfiẓ al-ʿIrāqī stated that among those who explicitly affirmed its recommendation was al-Ghazālī in al-Iḥyāʾ, in the chapter on devotional litanies, noting that there is no tasleem between them — meaning there is no break between each pair of rakʿāt."
The time of the sun's decline (zawāl) marks the very beginning of the time for the Ẓuhr prayer.
And Allah the Almighty knows best.
What is the ruling on vomiting, and does it invalidate ablution?
Vomit is impure (najis). Its exit is not considered one of the nullifiers of ablution. However, the mouth must be washed and purified from it, and any that gets on clothing or the body must be washed for prayer, because prayer is not valid with impurity present on the body or clothing. And Allah the Almighty knows best.