It should be clear that marriage in Islam is a solemn contract for which the Shari`ah lays down rules and arrangements to guarantee its stability. Among these rules is that the husband bears the responsibility for the full maintenance of the wife. He must carry out this duty cheerfully, without reproach, injury, or condescendence. Allah Almighty says: “Let him who hath abundance spend of his abundance, and he whose provision is measured, let him spend of that which Allah hath given him. Allah asketh naught of any soul save that which He hath given it. Allah will vouchsafe, after hardship, ease‏” (At-Talaq: 7).
Responding to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “In Islam, it is the duty of the husband to provide for the expenses of his wife according to his means and ability and his own personal circumstances. Allah says, “Men are leaders over women, because of the fact that Allah has favored one over the other, and because of the fact that they spend out of their wealth upon them” (An-Nisaa’: 34).
The question of how much to spend is determined by considering the standard of living as well as the ability and means of the persons concerned. Generally, it is considered the husband’s duty to provide food, clothes, shelter, and medicine, which are considered basic necessities.
As for whether the husband is bound to spend for his wife’s other expenses, this must be determined by considering the standard of life she is used to, as well as the means of the husband. If she belongs to a social group whose standard of living is higher, that must be taken into account; however, he is not to be burdened with what is beyond his ability or means. The more affluent shall be required to spend liberally, but a person in strait circumstances shall be required to spend only according to his means.
When Hind came to the Prophet (peace and blessings be upon him) to complain about her husband, Abu Sufyan, regarding his stinginess, she asked if she was allowed to take from his wealth without his permission. The Prophet (peace and blessings be upon him) told her to eat of it in fair measure and give charity out of it in fair measure. According to Imam Al-Bukhari, a woman is permitted to entertain and feed others from her husband’s wealth in fair measure without waiting for his permission.
However, what we have said should not be confused with lavish spending. This would be the case if a woman were addicted to compulsive buying without considering the circumstances of her husband and his priorities in spending. A man may have other priorities, besides non-essential expenditures for his wife, such as obligations toward his parents or poor relatives who may be dependent on him for one reason or another. A believing wife, therefore, should decide what is fair by visualizing herself standing before Allah and asking herself whether such a spending can be justified before Allah Who sees, hears and knows all things.”