[of] delivery and/or payment", again questioning the existence of riba al-fadl. (Ibn Rushd also reportedly agreed that according to Ibn ‘Abba, Muhammad did not accept riba al-fadl because, "there was no Riba except in credit". But according to Mahmoud A. El-Gamal, Ibn Rushd later reversed his position.) (There are also contradictory ahadith on trading silver for gold: one stating: "... The bartering of gold for silver is Riba except if it is from hand to hand and equal in amount...", while others say: "the Prophet ... allowed us to sell gold for silver and vice versa as we wished.") Application Islamic jurists have traditionally interpreted the admonition of riba by the ahadith to mean that if one amount of commodity is traded for the same kind of commodity then the two items exchanged must be of the same quantity, ignoring the quality of the commodity or the labor added to it. (Although there is some question of why anyone would ever exchange equal quantities of the same quality commodity -- "like for like"—that the ahadith seems to call for—for example 100 kilograms of wheat for 100 kg of wheat.) If, for example, a jeweler is paid in gold bullion for a gold ornament or piece of jewelry, and charges any money for their labor, they are guilty of riba al-fadl. If someone has a 100 grams of 24 karat gold and needs 100 grams of 18 karat gold (and can only get it by trade with their gold), they must trade their 100 grams for an equal amount of that less pure gold or commit riba al-fadl. All the schools of Islamic jurisprudence (fiqh) accept this prohibition. In more recent times, the International Institute of Islamic Economics 1999 Blueprint of Islamic financial system including strategy for elimination of riba, declared riba al-fadl forbidden under Islamic law, defining it as exchange transactions of the `same general kind` where there are `qualitative differences`. The Concise Dictionary of Islamic Terms (1979) also states that riba al-fadl is one of two kinds of riba which are "strictly forbidden by the laws of Islam". While all the schools of fiqh agree with the prohibition, they do not agree over its rationale or whether it is restricted to the six commodities mentioned in ahadith—gold, silver, wheat, barley, date, salt—as the ahadith do not say "whether or not other commodities will assume the same status". Imam Abu