I've reached mine, too. From what I understand you can't lend with interest and you can't lend what you don't own (https://en.wikipedia.org/wiki/Islamic_banking_and_finance).

The article says that Muslim financing tradition prevents banks from paying interest, and they must instead share their profits. In recent years this has been higher than the meager interest offered by banks' traditional savings accounts, so it is attracting non-Muslims at a growing rate. There is some debate as to whether all of these products technically fit the definition/custom--as some banks are advertising a certain rate of return through profit sharing, making it very similar to interest.