Is it permissible to agree with a butcher to purchase the meat of an animal after it has been slaughtered — for instance, by buying the meat of a sheep at a price determined by the weight of its meat following slaughter, at a fixed rate per kilogram? And what is the ruling if the animal is being purchased with the intention of it being an uḍḥiyyah (sacrificial offering)?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
It is not permissible to sell livestock in the manner of pricing each kilogram of meat after slaughter at a fixed rate, because the meat within the animal prior to slaughter is unseen and unknown. This leads to jahālah (ignorance of the subject matter) and gharar (contractual uncertainty), both of which are among the invalidating factors in sales transactions.
However, it is permissible for the buyer to issue a promise to purchase the meat of the animal after slaughter at a specified price per kilogram, with the actual sale being concluded at the time of weighing the meat — at which point both the quantity of the goods and the total price become known. There is no Sharī'ah objection to this arrangement.
The jurists have stipulated that for a sale to be valid, both countervalues must be present and observable. Al-Khaṭīb al-Shirbīnī, may Allah have mercy upon him, states:
"It is valid to sell a heap of grain whose total measure is unknown to both contracting parties at a rate of one sā' per dirham. This sale is valid because the subject of sale is present and observable, and ignorance of the total price is not harmful since it is known in detail — and uncertainty is thereby lifted."— [Mughnī al-Muḥtāj, Vol.2/P.355]
As for the uḍḥiyyah, the 'aqīqah, and vowed blood sacrifices (al-dam al-mandhūr) — full ownership of the animal must be established prior to slaughter. It is not valid for such animals to be slaughtered while still in the ownership of the butcher. Rather, the animal must be purchased alive and then slaughtered with the intention of uḍḥiyyah or the like. And Allah Almighty knows best.
What is the ruling on speaking while relieving oneself?
It is disliked for one relieving himself to speak while doing so, except out of necessity. And Allah the Almighty knows best.
How do I deal with whispers (waswasa) in ablution and purification?
Whispers in ablution are from Satan, and the Muslim should not pay attention to them. He is not required to re-perform ablution or repeat washing a limb because of waswasa. He should always base his purification on its being valid. It is recommended for him to frequently say "La ilaha illa Allah" (There is no god but Allah), because Satan recoils when Allah is mentioned. And Allah the Almighty knows best.
Is it permissible to offer prayer at home, or should it be offered in the mosque?
All perfect praise be to Allah, The Lord of The Worlds. It isn`t preferable for the man to pray at home as praying in the mosque is twenty seven times more rewarding. Therefore, this should motivate him to offer prayers in the mosque. And Allah Knows Best.