لا نسلم أن التقابض شرط في النقود، بل الشرط تعيينها
We do not concede that immediate reciprocal possession is the relevant condition in every monetary transaction under discussion; identification of what is exchanged may be the operative condition.
Classical examples involving money and food distinguish conditions of contract validity from conditions that identify the price or subject matter. The opponent may concede a need for certainty while denying that the evidence proves one uniform rule of immediate reciprocal possession.
Before applying such an analogy, determine the type of contract and the nature of both countervalues. Their common label as a “sale” does not settle every condition.