The “session of contract” refers to the very place where the exchange occurs, whether the parties are seated, walking, or riding, while “separation” is whatever people, by common custom, deem to be a parting.

When the two commodities exchanged belong to the same genus, parity must be achieved according to the Sharīʿah standard—namely, measurement by volume for grains, fruits, and liquids. Hence it is invalid to sell the moist form of a commodity for its dry form, its raw state for its cooked state, or its whole grain for its flour, and the like—anything that produces differing qualities that preclude precise equivalence between two ribā commodities of one genus. Al-Wazīr said: “They are unanimous that nothing sold by weight may be exchanged for its own genus except by weight, and nothing sold by measure except by measure, because parity cannot be ensured except through its Sharīʿah standard. As for what cannot feasibly be measured by volume—such as dates saturated with water—it is assessed by weight.” Shaykh Muḥammad ibn Ibrāhīm Āl al-Shaykh added: “Packed (maknūz) dates cannot be sold by volume; they must be sold by weight.”

Shaykh al-Islām held that the stronger view is that the effective cause of ribā in gold and silver is their quality as a price (thamaniyyah), not their weight, as asserted by the majority of scholars. The Council of Senior Scholars, in its resolution, stated: “To regard unrestricted thamaniyyah as the cause for ribā to apply to the two currencies is the view with the strongest evidence and the one most consonant with the objectives of the Sharīʿah. It is among the reported opinions of the Imams Mālik, Abū Ḥanīfah, and Aḥmad, and it is the preference of a number of leading scholars such as Shaykh al-Islām Ibn Taymiyyah, his disciple Ibn al-Qayyim, and others.” Likewise, the Fiqh Council of the Muslim World League, in its Resolution (6) dated 10/4/1402 AH, after discussing the matter of paper currency, ruled: “Since the original form of money is gold and silver, and since the effective cause of ribā in them is absolute thamaniyyah, according to the soundest opinion among the jurists, and in view of—”