Wife disposing of her own money without her husband’s knowledge
Question

                My sister works in Saudi and wants to invest part of her salary in a project on the basis that this money is my money and she will give me the profits whilst the capital remains hers, on the basis that I will lend her this money and she will invest it, but without her husband’s knowledge. Is she or am I doing anything haraam? Please advise us.
Praise be to Allah.There is no 
    sin on your sister if she gives you money as a loan for you to invest and 
    benefit from the results on the basis that the capital will remain your 
    sister’s. But if your sister wants to share the profit with you whilst she 
    is keeping the capital as is, that is not permitted, because this comes 
    under the heading of “every loan that brings benefits is riba.” It is not 
    necessary for her husband to know about your giving her the money, because 
    the money is her own and he has no right to any part of it unless she gives 
    it willingly. Allaah says (interpretation of the meaning): 
“And give 
    to the women (whom you marry) their Mahr (obligatory bridal-money given by 
    the husband to his wife at the time of marriage) with a good heart; but if 
    they, of their own good pleasure, remit any part of it to you, take it, and 
    enjoy it without fear of any harm (as Allaah has made it lawful)”
[al-Nisa’ 
    4:4]
But by way of kind 
    treatment and because men are more experienced and kanowledgeable in matters 
    of business, our advice is that the husband should be told about what his 
    wife is doing and how she is disposing of her wealth. 
Shaykh 
    ‘Abd-Allaah al-Jibreen said: 
The wife 
    owns her wealth and she has the right to dispose of it. She may give it as 
    gifts, give it in charity, pay off her debts, give up her rights to money 
    that she is owed or give up her right to inheritance to whomever she wants, 
    whether relatives or others. Her husband has no right to object if she is 
    mature and of sound mind. Her husband does not have the right to dispose of 
    any of her wealth except with her consent. (Fataawa al-Mar’ah al-Muslimah, 
    2/674).
 And Allaah knows best.