What is the ruling on making up the regular pre-Dhuhr *sunnah* (*al-sunnah al-rātibah al-qabliyyah*) for one who missed it in the Dhuhr prayer?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Every timed supererogatory prayer (nāfilah) is recommended (mandūb) to be made up if its time passes. As for a nāfilah that precedes the obligatory prayer, performing it before the farḍ is a matter of proper etiquette (adab); if it is prayed after the farḍ, it is still considered adāʾ (performed within its time). If the time of the farḍ has ended, it is recommended to make up (qaḍāʾ) the nāfilah for one who did not pray it.
Whoever misses the sunnah before Dhuhr, whether with an excuse or without one, it is recommended for him to pray it after the obligatory Dhuhr prayer, within the time of Dhuhr, even at its end, and it counts as adāʾ, not qaḍāʾ. It is also recommended for one who missed the pre-Dhuhr sunnah to pray it before the post-Dhuhr sunnah, in observance of the proper order. It is stated in ʿUmdat al-Sālik wa ʿUddat al-Nāsik (Vol.1/p.60): "What precedes the obligatory prayer has the same time as the obligatory prayer, and performing it before the farḍ is a matter of etiquette; after it, it is adāʾ. What follows the farḍ has its time begin with the performance of the farḍ and end with the end of its time."
If the time of Dhuhr has ended, it is recommended for him to pray both the pre- and post-Dhuhr sunnahs, and they count as qaḍāʾ for both. It is stated in ʿUmdat al-Sālik (1/61): "Every timed nafl, such as the ʿĪd prayer, Duha, Witr, and the regular rawātib of the obligatory prayers, if it is missed, it is recommended to make it up forever." And Allah Almighty knows best.
Is it permissible for a sick person to pray while sitting on a chair?
All perfect praise be to Allah, The Lord of the Worlds It is permissible for a sick person, who is unable to stand up, to offer prayer while sitting on a chair. If he/she was unable to prostrate while on the chair, the he/she should pray while sitting on the ground, but if he/she was neither able to bow (Roku),nor to prostrate, then he can do them while sitting on the chair. And Allah Knows Best.
What is the ruling on praying behind a disliked Imam?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is mildly disliked (Makruh Tanzihan) for a man—other than the permanent designated Imam (Imam Ratib)—to lead people in prayer if the majority of them dislike him due to a religiously blameworthy reason (Amr Madhmum Shar‘an), such as associating with open sinners (Fussaq), for example. As for the followers who dislike him, the prayer behind him is not disliked for them. However, if less than the majority dislike him, or if the majority dislike him for a reason that is not religiously blameworthy, then his leading the prayer is not disliked. And Allah the Exalted knows best.
Which hour coincides with the last third of the night?
This hour could be figured out by calculating the number of night hours which start at sunset, and end at dawn break, then the total is divided on three to get the result.