The ruling on Utilizing Trust and investing them
Question:
A person entrusted a sum of money to me and I used this money to invest, then when the owner of the money came to me, I returned his money to him in full, but I did not inform him of how I had benefited from his money, was my use of it permissible or not?
Answer:
If someone entrusted a sum of money to you, then you are not allowed to use it except with his permission and it is incumbent upon you to take care of it, just as you would take care of anything else, but if you used it without permission, you must ask him permission, and if he agreed (then well and good), but if he did not, then give him the profit on his money, or come to an agreement with that you will pay him half or so, because it is permissible for the Muslims to make settlements between them, unless it is a settlement which forbids what is permissible or permits what is forbidden.
Source:
Shaykh `Abdul-`Azeez Bin Baz
Fatawa Islamiyah Darussalam Vol: 5 no. 22
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