What is the ruling of Sharia on a wife secretly saving money from her husband, while contributing with it to the household needs, if the money is not from the husband's wealth but rather obtained from her family, and the husband is extravagant and cannot be informed for fear of consequences?

A woman may dispose of her wealth as she wishes, whether through saving, spending, giving charity, withholding, selling, or buying, for she has ownership of her wealth. Allah has affirmed this in the Quran, saying: (But if they, of their own accord, remit any part of it to you, take it and enjoy it with good cheer) and His saying: (And it is not lawful for you to take anything of what you have given them, unless both fear that they will not be able to keep within the limits ordained by Allah).

Here are two points to note: 1. It is not permissible for a woman to take anything from her husband's wealth without his permission, unless he is withholding her obligatory maintenance, in which case she may take what is sufficient for her maintenance in a reasonable manner. 2. If a woman has saved wealth that reaches the nisab (threshold) for zakat, she is obligated to pay zakat on it.