Is it permissible to conclude a sale before receiving possession (qabd) when exchanging two items subject to the prohibition of usury (riba) of excess, if both items share the same underlying cause of usury?

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The contract is void if the parties separate before taking possession. This is the view held by Al-Shafi'i. The evidence rests upon the Prophet's saying: "Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, like for like, equal for equal, hand to hand." (Reported by Muslim). Further support is found in the saying: "If these categories differ, then sell as you wish, hand to hand." The incident involving Malik ibn Aws al-Haddathan and Talhah ibn Ubaydullah, witnessed by Umar, confirms the requirement of immediate handover, as Umar forbade separation until physical receipt occurred. This is because when two items sharing the same cause of usury are exchanged, separation before possession is prohibited, similar to gold exchanged for silver.