A Muslim-non-Muslim partnership

A: If a trader, Christian or otherwise, deals in unlawful products or unlawful transactions, it is not permissible to become their partner or invest money with them. However, if they deal in lawful products and transactions, (Part No. 14; Page No. 288) there is nothing wrong with becoming their partner or investing money with them for a known percentage of the net profit, if profit is achieved, such as a third, a quarter, or more or less. As for taking a guaranteed fixed sum of interest, this is not permissible, as it is obvious Riba, which comes under the same ruling as a loan in which interest is stipulated. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.