What is the ruling on asking a friend for money with the intention of trading with it without informing him of that, and merely requesting the amount out of need, while pledging to return it in full without increase or decrease?

It is not a condition to inform the lender of the purpose of borrowing, but it is obligatory to inform him of the inability to fulfill the debt if the borrower is unable to repay. It is not permissible to borrow for one who is not in dire need if he does not expect to repay, unless the lender is aware of his condition. The Prophet, peace and blessings be upon him, emphasized the seriousness and consequence of debt. Whoever dies owing a debt will not enter Paradise until his debt is repaid.