items whose benefits are similar cannot be sold with tafadul (difference in quantity). This is refuted by the statement of the Prophet (peace and blessings of Allah be upon him): "Sell gold for silver as you wish, hand to hand; and sell wheat for dates as you wish, hand to hand; and sell barley for dates as you wish, hand to hand" (31). In one narration: "If these types differ, then sell as you wish, provided it is hand to hand." Narrated by Muslim and Abu Dawud (32). This is because they are two different types, so tafadul between them is permissible, just as it is when their benefits are distant. There is no disagreement regarding the permissibility of tafadul in gold for silver, despite the proximity of their benefits.

As for nisa' (delay in delivery): Every two types in which Riba occurs due to a single effective cause ('illah), such as items measured by volume for items measured by volume, items measured by weight for items measured by weight, or edible items for edible items, according to those who use these as an effective cause, it is prohibited to sell one for the other with nisa', without any disagreement that we know of. This is due to his (peace and blessings of Allah be upon him) statement: "If these classes differ, then sell as you wish, hand to hand." In one narration: "There is no harm in selling gold for silver, even if one is greater than the other, hand to hand; but as for nisa', then no. And there is no harm in selling wheat for barley, even if one is greater than the other, hand to hand; but as for nisa', then no." Narrated by Abu Dawud (33). This is unless one of the two compensations is the price (thaman) and the other is the priced item (muthamman), in which case nisa' is permitted between them without disagreement, because the Sharia has made concessions regarding Salam (forward sale), and the base for capital is dirhams and dinars; if nisa' were prohibited here, the door to Salam in weighted goods would be closed in most cases. As for if their effective causes differ, such as items measured by volume for items measured by weight, like selling meat for wheat, there are two narrations. The first: nisa' is prohibited between them, which is what al-Khiraqi mentioned here, because they are both properties from which Riba is derived, so nisa' is prohibited between them, like items measured by volume for items measured by volume. The second: nisa' is permitted between them. This is the opinion of al-Nakha'i, because they did not combine in one of the two attributes of the effective cause for Riba al-Fadl, so nisa' is permitted between them, like garments for animals.