Legal basis:
People's Republic of China (PRC) Civil Code
Article 675 The borrower shall repay the loan within the agreed time limit. If the term of the loan is not agreed or clearly agreed, and cannot be determined according to the provisions of Article 510 of this Law, the borrower may return it at any time; The lender may urge the borrower to return it within a reasonable period of time.
Article 680 usury is prohibited and the loan interest rate shall not violate the relevant provisions of the state.