As for the jurists’ disagreement over selling superior quality for inferior quality within ribā-liable goods, it can be illustrated by the sale of a single, medium-grade portion of such a commodity for two portions: one better than the medium and the other worse. An example would be selling two measures of average dates for two measures of dates, one of higher grade and the other of lower. Mālik invalidates the contract because he suspects that the seller’s real intent is to exchange two measures of average dates for a single measure of fine dates, using the inferior dates as a pretext to legalise what ought not to be allowed. Al-Shāfiʿī concurs, yet—insofar as I understand—not out of this suspicion, for he does not base rulings on mere misgivings. Rather, he appears to look at the qualitative disparity itself: whenever the increase represented by the superior dates over the average is not equal to the deficiency represented by the inferior dates below the average, true equivalence of quality is lacking.

From the same category stems their dispute over selling one ribā-liable commodity for its like together with some non-ribā merchandise, or with dinars or dirhams, in cases where the portion accompanied by that extra item is smaller than the single portion of the commodity alone; or where each side includes an accessory article and the two commodity portions differ in quantity. The first case would be, for instance, selling two measures of dates for one measure of dates and a dirham; the second, selling two measures of dates and a garment for three measures of dates and a dirham. Mālik, al-Shāfiʿī, and al-Layth hold such transactions impermissible, whereas Abū Ḥanīfah and the Kufan jurists deem them permissible. The crux of the disagreement is whether the share of the ribā commodity that is counter-balanced by the accessory item must equal it in value, or whether the consent of the two parties alone is sufficient.

Those who insist upon equal value say the sale is invalid because that value is unknown: if the accessory item does not match precisely the surplus of one ribā commodity over the other, disparity necessarily results. For example, if someone sells two measures of dates for one measure of dates and a garment, the garment would have to be worth the measure; otherwise inequality is unavoidable. Abū Ḥanīfah, however, is satisfied so long as both parties agree. Mālik also invokes the principle of blocking the means, arguing that people use this device to disguise a surplus sale within the same commodity. These are the best-known issues in this field.

Chapter: Sales employed as devices leading to ribā

A further situation may arise between two contracting parties when one of them says to the other, “with an increase” or “with a decrease,” or when one of them buys back from his counterpart the very item he previously sold to him at a higher or lower price. Without intending it, the two might thereby create a ribā transaction—such as when a person sells an item to someone else for ten dinars cash, then repurchases it from him for twenty dinars on deferred terms. When the second sale is added to the first, the net result is that one of them has handed over ten