Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.
What is the ruling on selling sacrificial animals (udhiyah) described with specific attributes and authorizing an agent to slaughter them?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Selling sacrificial animals (udhiyah) that are described with specific attributes is permissible. This falls under the category of a salam sale (forward sale) if conducted using the terminology of salam, and under the category of a regular sale if not using the terminology of salam.
As for authorizing the seller to slaughter the sacrificial animal, the basic principle is that it is permissible, because the agent (wakil) stands in the place of the principal (muwakkil) in achieving his objective. This is a contract that the principal (the buyer) is entitled to perform himself, so authorizing another (the seller) to do so on his behalf is valid.
However, it is a condition for authorization to slaughter that the intention (niyyah) is present either at the time of slaughter or at the time of handing over the sacrificial animal to the agent. The basic principle is that the sacrificial animal must be specifically designated, as it is an act of worship. It is not required to designate it at the time of slaughter; rather, it is valid to do so before that.
It is permissible for the principal either to delegate the intention to the agent or to formulate it himself when authorizing the agent to slaughter. However, the sacrificial animal must be designated, even if at the time of slaughter, by the agent.
It is obligatory to designate the sacrificial animals so that each person offering a sacrifice receives his own specific animal. Therefore, charitable organizations and companies must take this into consideration and establish a specific mechanism that ensures no mixing of sacrificial animals occurs, so that each person offering a sacrifice receives his own designated animal. And Allah Almighty knows best.
What is the ruling of Islamic Law if the follower (maʾmūm) stands up for the third rakʿah out of forgetfulness while the imam has sat for the middle tashahhud?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
If the imam sits for the tashahhud while the follower (maʾmūm), out of forgetfulness, stands up for the third rakʿah, he is obliged to return to his sitting position, since following the imam is obligatory. In this case, no prostration of forgetfulness (sujūd al-sahw) is required of him. If, however, he fails to return, his prayer is rendered invalid.
Shaykh al-Islām Imām Zakariyyā al-Anṣārī, may Allah have mercy upon him, states: "If the follower stands up alone out of forgetfulness, he is obliged to return, since following the imam is obligatory... If he does not return, his prayer is rendered invalid, due to his departure from what is obligatory." [Asnā al-Maṭālib,Vol.1/P.190] And Allah the Almighty knows best.
When does the time for the 'aqīqah lapse and pass?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
If the guardian was financially capable (mūsir) during the majority of the postnatal period (nifās) — which is sixty days — then the obligation of the 'aqīqah remains upon him until the child reaches the age of maturity (bulūgh). Once the child reaches maturity, the demand falls away from the father and those like him. At that point, it becomes Sunnah for the child himself to perform the 'aqīqah on his own behalf.
However, if the guardian was financially incapable (mu'sir) during the postnatal period, and then became financially capable after its expiry — that is, after sixty days — the 'aqīqah is no longer required of him. And Allah Almighty knows best.