What is the established measure for one Wasaq (Usquf)?

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There is no disagreement that one Wasaq equals sixty Sa's. This consensus is attributed to every recognized scholar according to Ibn al-Mundhir. Evidence for this is found in a hadith narrated by al-Athram, from Salamah ibn Sakhr, from the Prophet, peace be upon him, stating: 'The Wasaq is sixty Sa's.' Similar narrations affirming this measure were reported by Abu Sa'id and Jabir from the Prophet, peace be upon him, and recorded by Ibn Majah.