What is the definition and measure of 'Two Qullahs'?
Chapter on what purification is achieved with regarding water
Al-Mughni
Book of Purification
Primary text
The Qullah signifies a large water vessel, named because it is carried (Tuqallu). The measure intended here is two Qullahs of Hajar, equating to five full water skins (Qirb), with each skin being one hundred Ritals by the Iraqi measure, totaling five hundred Ritals. This measurement is the apparent position of our scholars and Imam Al-Shafi'i. The specificity to Qilal of Hajar is due to a transmitted Hadith mentioning it explicitly and because these vessels were the largest and most famous known containers during the Prophet's era, ensuring the limit is established upon a known quantity.
Supporting text
Imam Ahmad narrated through other chains that two Qullahs equal four Qirbs. Those who uphold measuring water volume by Qirbs universally agree on equating one Qirb to one hundred Iraqi Ritals. Abu 'Ubayd held that the term refers to the large water bags (Hibaab) due to their common knowledge and size, suggesting that any established measure should refer to the largest possible unit for greater certainty.