for its own kind in an unspecified bulk, nor to sell something sold by weight for its own kind in an unspecified bulk, because equality cannot be ascertained, and ignorance of equality is tantamount to knowing that there is an excess.

Currency exchange (ṣarf) is the sale of one form of currency for another, whether the two are of the same type or different, and whether the currency consists of gold, silver, or the paper notes in use today, for these notes take the same ruling as gold and silver since they share the same effective cause of riba, namely their function as a medium of exchange. When one currency is exchanged for the very same currency—gold for gold, silver for silver, or paper notes for an identical denomination, such as dollar for dollar or Saudi riyal notes for Saudi riyal notes—two conditions become obligatory: equality in amount and mutual possession within the same sitting.

If one currency is exchanged for another of a different kind—such as Saudi riyal notes for U.S. dollars, or gold for silver—only one requirement remains: the exchange must be on the spot with reciprocal possession before the parties separate, while disparity in amount is permissible. The same ruling applies when gold jewelry is sold for silver coins or for paper money: immediate settlement and mutual possession in the same gathering are required, and likewise when silver jewelry is sold for gold.

However, if gold or silver jewelry is sold for jewelry or currency of its own kind—gold jewelry for gold, or silver jewelry for silver—then two obligations apply: equality in weight and immediate, reciprocal possession in the same sitting.

The danger of riba is immense, and it cannot be avoided except through knowledge of its rulings. Whoever cannot acquire this knowledge himself must ask the people of knowledge, and he is not permitted to enter any transaction until he is certain that it is free of riba, so that he may safeguard his religion and