A woman should be sincere in spending the money her husband gives her because she is entrusted with it. She can spend from the money freely so long as her husband has given her a general permission and so long as she is spending in things that would not upset him. In this case, both the husband and the wife will be rewarded for paying alms.
Dr. `Abur-Rahman Al-`Adawi, Professor of Fiqh at Al-Azhar University, states the following: “It is the responsibility of the husband to spend on his wife and children according to his financial means. This goes along with Allah’s words: “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).
this is a promise from Allah and it can never be breached. In another Qur’anic verse, Allah says: “But lo! with hardship goeth ease, Lo! with hardship goeth ease.” (Ash-Sharh: 5-6)
the righteous women who lived at the lifetime of the Prophet (peace and blessings be upon him) had a staunch belief in Allah’s promise; therefore, they never got distressed due to financial problems. Besides, they were satisfied with whatever Allah had ordained, and those Muslim women believed that distress didn’t last long and that ease was coming soon.
In addition, the husband who is able to provide his wife with monthly expenditures should thank Allah for the sustenance He grants him. Nevertheless, when the wife has a general permission to spend the money in the way she sees fit, then she is allowed to give alms. Accordingly, she will be rewarded as well as her husband; each will get his or her reward in full. On the other hand, if the wife doubts that her husband would approve of giving away such alms, she should inform him of her intention to spend on the house as well as giving alms to the poor.
If it happens that the husband refuses that part of the money be given as alms, then the wife may ask for money for herself that she could manage freely. Hence, if the husband approves, the wife can give alms to whomever she wants, but if he refuses then she will be rewarded for her good intention. The Prophet (peace and blessings be upon him) said, “The reward of deeds depends upon the intentions and every person will get the reward according to what he has intended.””