Is it permissible to offer Salah (prayer) on behalf of the sick who is on his/her death bed, and is incapable of offering it?
It`s impermissible to offer Salah on behalf of the sick, or the dead.
Is permissible to include a will requesting that a Holy Qur'an buried along with me?
It is not permissible to include a will requesting that a Quran be buried with the deceased in their grave. This is because the body of the deceased typically decomposes and may release impure substances, and it is not allowed to expose the Quran to impurity. Intentionally desecrating the Quran is an act of disbelief. Instead, read the Quran during your lifetime, as it will benefit you after death. And Allah Knows Best.
Does Husband fasting while being impure for having sexual intercourse with his wife at night permissible?
Yes it is permissible for you to fast because impurity isn't among valid fasting conditions, but you are obliged to perform ritual impurity in order to catch up Fajr prayer at its due time. And Allah Knows Best.
I am a doctor, and sometimes I refer patients to the hospital for surgical interventions, and they give me a commission from the fees of the surgeries, even though I do not perform these surgeries. What is the ruling?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.
If this commission is charged to the patient as part of the operation costs, then it is not permissible. Additionally, a doctor should only recommend surgery if there is a genuine medical need, and the hospital should only perform an operation when necessary. And Allah The Almighty Knows Best.
