What is the established measure for the Sa' (Saa') regarding religious dues?
Chapter on Zakat al-Fitr
Al-Mughni
Book of Zakat
Primary text
The established measure for the Sa' is five ratls and one-third using the Iraqi measurement system. Scholars determined this measure by weight for ease of preservation and transfer. Imam Ahmad measured a Sa' using wheat and found it to be five ratls and one-third. This was further confirmed by measuring lentils, which are stable and do not compress, yielding the same weight, establishing it as the most reliable measure for the Prophet's Sa'. If heavier grains yield this weight, then lighter grains measured by weight will result in a measure exceeding one Sa'.
Supporting text
Muhammad ibn al-Hasan stated that paying five ratls and one-third of wheat is insufficient because wheat varies in density (light and heavy types). Al-Tahawi suggested paying five ratls of items whose measure is consistent by volume and weight, such as raisins and mash. The implication is that paying eight ratls of a heavier item would not suffice without adding an amount known to reach the level of a Sa'.