To what extent is the husband’s father entitled to interfere in his son’s wife’s life and decisions, especially regarding buying furniture, leaving the house, or buying gifts for her family?

The fundamental principle is that spouses have an independent life, and no one has the right to interfere in it. A wife is commanded to obey her husband in what is right, not to obey his parents. The husband's father has no right to interfere in the couple's affairs, nor to prevent the wife from buying gifts for her family from her own money. If the purchase is made from the husband's money, it is not permissible except with his permission. The father does not have the right to compel his son to buy gifts for his siblings from his (the son's) money, because one of the conditions for a father to be permitted to take from his son's money is that he does not take to give to his (the son's) siblings. The husband is advised to deal wisely with his father, showing him dutifulness and obedience in what is right, without oppressing his wife.