The composite correspondence is:
10 dirhams ← 10 dirhams: equality in a same-metal component
1 dirham ← 1 dinar: unequal quantities allowed across gold and silver
Calling the whole 11-to-10 correspondence usury without allocating the dinar misses this ruling. Conversely, inventing a nominal mixed bundle cannot legalise a genuinely unmatched same-metal excess.
Opening interactive controls...
Equality within the same-metal portion
Bab al-Sarf: Mixed Currency Exchanges, Debased Coins and Obsolescence
The composite correspondence is:
10 dirhams ← 10 dirhams: equality in a same-metal component
1 dirham ← 1 dinar: unequal quantities allowed across gold and silver
Calling the whole 11-to-10 correspondence usury without allocating the dinar misses this ruling. Conversely, inventing a nominal mixed bundle cannot legalise a genuinely unmatched same-metal excess.