Riba in the rulings: the forbidden excess in exchange and in delay, its kinds, its causes and its rulings

Riba is excess in the lexical sense. In the jurists' usage it is an excess on one of two counter-values in an exchange, or an excess on a debt in return for delay; the schools define it in different words. ^{1 2} It is forbidden by the Qur'an, the Sunna and consensus, and is a major sin, counted among the seven destructive sins. ^{3 4}

Whoever makes riba lawful has disbelieved; whoever deals in it without regarding it as lawful is a sinner. Ignorance neither removes the sin nor prevents the consequence. ^{3 14} Whoever lends, sells or buys must learn the rules before he deals. ¹⁴

The commentators give reasons, among them that riba takes a person's property without a counter-value, turns people from earning, and cuts off good lending between them. ^{15 16}

The Hanafis, Malikis and Hanbalis divide riba of sale into excess and delay, and the Shafi'is into three: excess, delay of receipt, and delay by term. ^{5 6} Riba of delay is called the clear riba and the riba of the pre-Islamic period; riba of excess is called the hidden riba, because it is a means to delay. ^{6 17}

The six items named in the hadith of Ubada ibn al-Samit (may God be pleased with him) are gold, silver, wheat, barley, dates and salt, and the scholars agree that excess in them is forbidden when paid for in delay. ^{7 18} Most jurists extend the rule to items sharing its cause; the schools differ on the cause. The Hanafis take it as kind together with measure, the Malikis take gold and silver as a medium of exchange and foodstuffs as storable staples, the Shafi'is take gold and silver as the kind of money and foodstuffs as edible, and Ahmad is reported in three versions. ^{8 9 19 20 10}

The schools differ in the exchange of one kind for the same kind, excess or delay, and in fresh dates against dried dates, and in meats, milks, fats and their sources. ^{21 22 23 11} A contract mixed with riba is void according to the majority, while the Hanafis call it a defective contract in which the riba is returned. ^{24 7} The Malikis allow a trader in urgent need to sell minted gold for coin within the limits of need, and the matter is disputed. ^{25 12}

They include the sale of 'inah, which the majority forbid as a means to riba; muhaqala and muzabana; the mixed sale of mud 'ajwa, where the majority hold riba is present and the Hanafis allow it on a division; and riba in the abode of war, where the majority and Abu Yusuf hold it forbidden as in the abode of Islam, while Abu Hanifa and Muhammad differ for a non-Muslim enemy. ^{11 25 12 13}

Sale, exchange and the salam contract are treated in their own entries, and so are the sales of time and 'inah. ^{2 11}