What is the ruling on taking a sum of money from a brother's wealth without his knowledge, in exchange for looking after his affairs, given that the studying brother is harmed by this?

This transaction is divided into two stages:

1. First Stage (without a specified wage or without any wage originally): If you worked voluntarily, you are not entitled to a wage. However, if you were not working voluntarily, you are entitled to "a fair wage" (أجرة المثل), estimated by experts and just individuals based on similar work and what people like you receive. The prevailing custom in your region will determine whether your work was voluntary or not. 2. Second Stage (with a specified wage): As long as you agreed to the stipulated wage, it is not permissible for you to demand an increase on the pretext that the work or harm is greater.

You must repent to Allah for purchasing shares for your brother in companies that deal in unlawful activities or mix their activities with unlawful ones. You should also advise your brother to repent and dispose of the unlawful returns from this investment.