The sale (ba’i) of a debt (dain/ dayn) for a debt. Broadly speaking, it involves the exchange of two objects, both delayed, or the exchange of a countervalue for another delayed countervalue. This term is used to describe several different ways of debt-for-debt exchanges. The most well known of these exchanges is the one in which a lender extends his debtor’s repayment period in return for an extra amount (riba or interest) over the principal. This type of sale is prohibited under shari’a and the Prophetic maxim (hadith) is definitive and outright in forbidding the sale of al-kali bil-kali, i.e., the exchange of one delayed countervalue for another delayed countervalue.

Ba’i al-kali bil-kali is also termed “ba’i al-dain bil-dain”.