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.
What is the ruling of Islamic Law on colleagues alternating overtime shifts and receiving wages for absent days?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
An employee is religiously obligated to abide by the instructions and regulations pertaining to overtime hours. Furthermore, it is mandatory to adhere to honesty and avoid deceit, circumvention, and falsehood. Allah Almighty says (what means): "O you who have believed, be conscious of Allah and be with those who are truthful."
(At-Tawbah/119).
Therefore, whoever is assigned to work overtime must remain present at the designated workplace, even if no active tasks are required of them during that time.
Likewise, the official authorized to approve overtime work must comply with all established conditions and regulatory guidelines. It is impermissible for them to grant overtime hours in violation of system regulations. Should any compensation be disbursed in contravention of these official rules, it is unlawful to accept or consume such wages. And Allah Almighty knows best.
Is Zakah (obligatory charity) obligatory on indebted merchant?
Debt doesn`t abrogate the dueness of Zakah, thus a debtor who has money, articles of merchandise, or other Zakah funds at his disposal should pay their Zakah.
Is it permissible for a woman to wear underwear while performing Umrah?
Yes, it is permissible for a woman to wear underwear while performing Umrah. This is because she should keep her regular clothes that cover all her body while being in a state of Ihram (ritual consecration) for Hajj, or Umrah. However, she should uncover her face and hands, but it is permissible for her to let her head-covering garment drape from her head down over her face when non-Mahram (i.e., marriageable) men pass by her. And Allah Knows Best.