After I had prayed, I found a drop of menstrual blood and was unsure when that happened; what is the ruling on my prayer and fast?
All praise is due to Allah, peace and blessing be upon the Messenger of Allah.
Your prayer and fast are correct ,and you should not make up for them, and we ask Allah, The Almighty, to duely reward you for these acts of worship. Your menses start once you see blood because the situation remains as such unless there is certainty or predominant conjecture, as per the Fiqh maxim: "Certainty is not removed by doubt". And Allah Knows Best.
A person bought a device through a usurious bank, and receives income from it every month after paying the bank for the price. Now the person regrets it, what should he do now?
This person has fallen into what is forbidden due to dealing with usury. He must repent sincerely, and whoever repents, Allah Will Accept their repentance. As for the device, there is no need to sell it. And Allah Knows Best
What is the ruling of Sharia on marrying the maternal niece of one`s wife?
All perfect praise be to Allah the Lord of The Worlds. May His blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
One may not combine in marriage a woman and her paternal aunt, or a woman and her maternal aunt, as stated the Prophet (PBUH). And Allah The Almighty Knows Best.
What is the ruling on a man leading his sisters in obligatory prayer, or Taraweeh prayer (Night prayer in Ramadan)?
The prayer of the man who leads his wife, or sisters in prayer is valid, but it is more rewarding for him to offer obligatory prayer in the mosque. And Allah Knows Best.