Abu 'Ubayd said: I know of no disagreement among people that the faraq is three sa's, and the faraq is sixteen ratls, so it is established that the sa' is five and a third ratls. It is narrated that Abu Yusuf entered Medina and asked them about the sa', and they said: Five and a third ratls. [He asked them for the proof] (8), and they said: Tomorrow. The next day, seventy elders came to him, each of them holding a sa' beneath his cloak, and said: My sa' I inherited from my father, and my father inherited it from my grandfather, until they traced it back to the Prophet (peace be upon him). Abu Yusuf retracted his opinion. This is a mutawatir (mass-transmitted) chain of narration that yields certainty, and it is established that the Prophet (peace be upon him) said: "The standard of measurement is the standard of the people of Medina" (9). It has not been established for us that it was ever changed, and this hadith of Anas was reported solely by Musa ibn Nasr (10), who is weak in hadith, as stated by al-Daraqutni (11).

Section: The Iraqi ratl is one hundred and twenty-eight and four-sevenths dirhams, which is ninety mithqals. A mithqal is one and three-sevenths dirhams. This was the case in the past; then they added a mithqal to it, making it ninety-one mithqals, which completed it to one hundred and thirty dirhams. They intended by this addition to remove the fraction of the dirham. The practice is based on the first [measurement], because it was what existed at the time the scholars used it to determine the mudd. Thus, the mudd at that time is one hundred and seventy-one and three-sevenths dirhams. In terms of the Damascene ratl, which weighs six hundred dirhams, this is three uqiyahs and three-sevenths of an uqiyah. The sa' is four mudds, so it is one ratl, one uqiyah, and five-sevenths of an uqiyah. If you wish, you may say: It is one ratl and one-seventh of a ratl.