of a denial of time value of money". Maududi has called the difference "between the psychological values of the present and the future ... nothing but an illusion", and disproven by the fact that few people "spend all their wealth on present pleasure and enjoyment." Taqi Usmai has declared unequivocally that "in Shariah there is no concept of time value of money". Irfan argues that the value of money diminishes very little over time because some consumption — such as eating — can only be done over time. Furthermore, discounting for time may lead to negative outcomes such as unsustainable agricultural production with planting and grazing that causes desertification and erosion, since these bad outcomes occur in the discounted future. However, Islamic banking also calls for rewarding delayed gratification in the form of "return on investment" and the sale of goods on credit (endorsed by early jurists such as Muhammad al-Shaybani). Most orthodox Islamic scholars and economists have taken a middle path — insisting that a rate of discount of money over time is an invalid concept if the rate is interest on a loan, but valid if the rate is return on capital from Murabaha or other Islamic contracts. Critic Farooq complains that this rationalization is contradictory, and amounts to denying time value in theory while embracing it in practice, and that the accepting of the theory in practice explains the large (and successful) move of non-Islamic western banks into Islamic banking. Islamic concept of money Answers to the argument (of economists such as Farooq) that lenders of money are due some kind of rent-like compensation; and to the question of why charging extra to finance a purchase (in, for example, murabaha Islamic finance) is allowed, but in lending cash it is riba, can be found (supporters believe) in the "Islamic concept of money". Orthodox scholars, such as M.U. Chapra and M.T. Usmani, have written that money can only be a "medium of exchange" and must not be treated as an "asset or commodity". Trading a commodity/asset, or paying a fee for its use is right and sensible (they argue), but trading or renting a medium of exchange is wrong, because money is "unproductive" has "no intrinsic utility". This being the case, no return for the use of money can be justified, and explains (at least in part) why it is riba. Usmani quotes condemnations of speculation by various