Is it permissible to repay a loan with an amount less than the principal amount borrowed?

Primary text

If one stipulates in the loan that he will repay less than what was borrowed, and the item is one where Riba applies, it is not permissible because it results in failing to maintain equality, which is a requirement in such transactions. If the item is not one where Riba applies, it is still generally not permissible because the essence of a loan implies the return of the equivalent, and stipulating less contradicts this essence, similar to stipulating an increase.