What is the ruling on performing voluntary (nafl) prayer during the time of istiwā' (the sun's zenith) on the day of Jumu‘ah (Friday), and is this ruling specific to someone who has come to the mosque to perform the Jumu‘ah prayer?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
It is permissible to perform voluntary (nafl) prayer during the time of istiwā' (the sun's zenith, i.e., its highest point before noon) on the day of Jumu‘ah (Friday) — whether for someone who is attending the Friday prayer or someone who is not, and whether they are among the people obligated to attend it or not.
It is stated in Mughnī al-Muḥtāj (Vol.1/P.310): "The more correct position (al-aṣaḥḥ) is that prayer is permissible during this time without restriction — regardless of whether the person will be attending the Jumu‘ah prayer or not." And Allah, the Exalted, 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 of Islamic Law on leaving the Sunnah prayer of Dhuhr due to fatigue?
Praise be to Allah, and peace and blessings upon our master, the Messenger of Allah.
According to the general rule, a Muslim should strive to maintain the Sunnah prayers before and after the obligatory prayers (al-sunan al-qabliyyah wa al-ba'diyyah). One is permitted to pray them sitting from the outset, but if one leaves them due to severe fatigue, there is no objection to doing so. It is recommended (mustahabb) to make up (qadā') a time-bound supererogatory prayer (nafl mu'aqqat) at any time if it was missed.
Al-Shirbīnī (may Allah have mercy on him) said: "If a time-bound supererogatory prayer is missed, it is recommended to make it up according to the more authoritative view (al-azhar), based on the hadith recorded in the two Ṣaḥīḥs: 'Whoever sleeps through a prayer or forgets it should pray it when he remembers it.' This is also supported by the fact that the Prophet (peace and blessings be upon him) made up the two rak'ahs of Fajr when he and his companions overslept in the valley and missed the dawn prayer until the sun had risen [narrated by Abū Dāwūd with an authentic chain]." And Allah, the Most High, knows best.
What is the ruling on brown discharge before the menstrual period? Is it considered part of menstruation (Hayd)?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Dusky discharge (Kudrah), reddish discharge (Humrah), and yellowish discharge (Sufrah) are all considered menstruation (Hayd) if they occur during the time of the menstrual cycle. If their duration exceeds a day and a night, and the period persists from the first sight of the discharge until the cessation of the menstrual blood—provided the total duration does not exceed fifteen days—then all of it is menstruation. However, if the duration exceeds fifteen days, then the discharge is not considered menstruation, but rather chronic irregular bleeding (Istihadah). And Allah the Exalted knows best.