What is the ruling on the business transaction I conducted with my friend, where I informed him that I possessed capital to acquire and oversee the goods, even though I did not possess any capital, and we agreed beforehand on a specific percentage of the profit?

You must repent to Allah for lying and defrauding, for what is with Allah cannot be attained through disobeying Him. A partnership established through lying and deception is invalid, and agreeing upon a fixed amount of profit is impermissible. In this case, the worker is entitled to a fair wage (اجرة مثله), and all profit belongs to the capital owner. Mudarabah (definition) (profit-sharing partnership) must be based on honesty and justice, while observing the regulations of legitimate Mudarabah.