and if one man owes another a single dinar, whether as a loan or as part of a sale price, Mālik rules that he may not take one half of it in a form whose value exceeds what he takes in the other half; the same principle applies to gold payments in general. Mālik did, however, allow a token act of courtesy—such as replacing a counterfeit dirham with a sound one—when the amount is trivial and the intention is purely charitable.
When the two parties conduct a weight-for-weight exchange of gold for gold or silver for silver and one side is found to be short, it is impermissible to make up the deficiency by adding silver to the gold side or gold to the silver side, for that would amount to exchanging gold and silver for gold.
The touchstone in any such weight-matched exchange is that the scales be perfectly balanced; the actual number of coins is immaterial, whether they be more or fewer. Likewise, no attention is paid to qualitative superiority between the two lots of gold or silver so long as the beam of the scale is level and neither lot contains an admixture of a different metal.
The same applies when the better lot contains some inferior pieces, provided the inferior pieces are comparable to—or better than—the gold offered by the counter-party; in that case the owner of the finer gold has derived no benefit from its superiority, and the transaction is perfectly acceptable.
If, on the other hand, the additional gold he brings is of poorer quality than the other party’s gold, the deal is invalid, for he is exploiting the excellence of part of his gold to rid himself of inferior coins—something Mālik classed as a form of gambling.
Everything discussed so far concerns a weight-for-weight exchange of two lots of gold or two lots of silver where one lot is better than the other, yet both the good and the bad belong to the same metal. The ruling does not extend to an alloy that contains a foreign element. If either the silver or the gold is adulterated with anything else, no kind of weight-matched exchange is permissible, for the inevitable disparity would constitute usury (ribā)—save for the small, benevolent concession that Mālik, may Allah have mercy on him, allowed purely as an act of kindness.