Western sources and the writings of the celebrated medieval Islamic scholar Al-Ghazzali that money was made to facilitate trade and should never be hoarded or used to charge interest. In response, M.A. Khan questions whether the distinction between asset and medium of exchange proceeds from a need "to prove that all types of interest are unfair", rather than from Islam; how money can be a medium of exchange but not an asset, asking what "the justification for charging" zakat (the Islamic religious tax) on money is "if money is not a store of value"; how cash balances are to be entered in modern business accounting if not as assets; if there is any good way for enforcers of Islamic law to differentiate between productive trading and the speculation which is forbidden by this definition. Early payment of debt The opposite of credit sales — i.e. higher charge for deferred payment — is reduced charges for early payment, and is hard to justify without an acknowledgment of the time value of money and the validity of interest on loans, according to some (such as M.A. Khan). Reduction of debt for early payment is considered haram by the four Sunni schools of jurisprudence (Hanafi, Maliki, Shafi'i, Hanbali), but whether there is a consensus of Islamic jurists is unclear. According to Ridha Saadullah, such reductions have been permitted by some companions of the Prophet and some of their followers. This position has been advanced by Ibn Taymiyya and Ibn al-Qayyim, and it has, more recently, been adopted by the Islamic Fiqh Academy of the OIC. The Academy decided that `reduction of a deferred debt in order to accelerate its repayment, whether at the request of the debtor or the creditor is permissible under Shariah. It does not constitute forbidden riba if it is not agreed upon in advance and as long as the creditor-debtor relationship remains bilateral. ... Inflation Whether or not compensation to lenders for the erosion of the value of the funds from inflation is allowed (and how to provide that compensation in a way that is not considered riba), has also been called a problem "vexing" Islamic scholars, since finance for businesses will not be forthcoming if a lender loses money by lending. Volume 1 of Investment Laws in Muslim Countries Handbook, states "an interest rate that did not exceed the rate of inflation was not riba according to classical