Is a woman sinful if she fasts out of shyness from her family while menstruating or in postnatal bleeding?
It is forbidden for a woman who is menstruating or in postnatal bleeding to abstain from food and drink with the intention of fasting. If she fasts out of shyness, she is sinful, as her fast is not valid.
However, if she refrains from eating and drinking without intending to fast, it is not forbidden, but she unnecessarily burdens herself without need.
Is it permissible to offer prayer at home, or should it be offered in the mosque?
All perfect praise be to Allah, The Lord of The Worlds. It isn`t preferable for the man to pray at home as praying in the mosque is twenty seven times more rewarding. Therefore, this should motivate him to offer prayers in the mosque. And Allah Knows Best.
What is the Du`a (supplication) of Istikhara (guidance prayer)?
O Allah, I consult You as You are All-Knowing and I appeal to You to give me power as You are Omnipotent, I ask You for Your great favor, for You have power and I do not, and You know all of the hidden matters. O Allah! If you know that this matter (then he should mention it) is good for me in my religion, my livelihood, and for my life in the Hereafter, or he said: "for my present and future life" then make it (easy) for me. And if you know that this matter is not good for me in my religion, my livelihood and my life in the Hereafter, or he said: "for my present and future life" then keep it away from me and take me away from it and choose what is good for me wherever it is and please me with it."
Is the Saying "Whatever is Taken by the Sword of Shyness is Forbidden" an Authentic Ḥadīth?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
The saying "Whatever is taken by the sword of shyness is forbidden" is not an authentic ḥadīth, though its underlying meaning is sound. The established sharʿī principle is that a Muslim's wealth is not lawful for anyone to take except with his wholehearted consent, as Allah the Almighty says {what means}: "O you who have believed, do not consume one another's wealth unjustly, but only [in lawful] business by mutual consent." [Al-Nisā/ 29] And the Messenger of Allah ﷺ said: "Listen to me and you will live well: do not wrong others, do not wrong others, do not wrong others. Indeed, a man's wealth is not lawful except with his full, willing consent." (Reported by Aḥmad in his Musnad.) Whatever is taken through the pressure of shyness or social embarrassment runs directly counter to genuine, wholehearted consent.
The jurists have explicitly stated that whatever is taken by means of the "sword of shyness" carries the same ruling as that which is taken by coercion — it must be returned to its rightful owner.
Ibn Ḥajar al-Haytamī, may Allah have mercy upon him, states in al-Fatāwā al-Kubrā (Vol.3/P.30): "Do you not see the reported scholarly consensus that whoever has something taken from him purely out of shyness, without his genuine consent, does not pass ownership of it to the one who took it? They reasoned that this constitutes a form of coercion through the 'sword of shyness,' comparable to coercion at the point of an actual sword. Indeed, many people would rather submit to the literal sword and endure the pain of its wound than submit to this first kind of coercion, out of fear for their dignity and standing — which people of sound judgment hold dear and guard most fiercely." And Allah the Almighty knows best.