Is grape vinegar (khal al-'inab) permissible to be sold for raisin vinegar (khal al-zabeeb)?
Chapter on Riba (Usury) and Exchange (Sarf)
Al-Mughni
Book of Sales
Primary text
Grape vinegar is treated like date fruit (tamr) regarding previous rulings, with one exception: grape vinegar must not be sold for raisin vinegar because each possesses a quality that the other lacks, implying they are distinct entities in this specific transaction. The permissibility of selling part of raisin vinegar for another part of raisin vinegar is established, analogous to date fruit.
Supporting text
The opinion held by Al-Thawri, Al-Shafi'i, Ishaq, Abu Thawr, and the Companions of the Opinion (Ahl al-Ra'i) is that they are distinct. Conversely, there is a transmitted view from Ahmad, Saad ibn Abi Waqqas, 'Abd al-Rahman ibn al-Aswad ibn 'Abd Yaghuth, Ibn Mu'ayqib al-Dawsy, Al-Hakam, Hammad, Malik, and Al-Layth, asserting that both types of vinegar constitute a single category (jins).