The measure of the sa

It is narrated from Sayyiduna al-Sa'ib bin Yazid (may Allah be pleased with him) that in their (the noble Companions') time, their customary sa' was equal to one mudd and one third of a mudd.
This report is sahih (authentic), and its basis is in Sunan al-Nasa'i.

It is narrated from Sayyidah Asma (may Allah be pleased with her) that she used to say: "In the blessed time of the Messenger of Allah (peace and blessings be upon him), we used to pay Sadaqat al-Fitr by that measure (the mudd) with which people generally carried out their buying, selling and trade with one another."

It is narrated from Imam Mujahid (may Allah have mercy on him) that he said (explaining the old Islamic weights): "One uqiyyah equals forty (dirhams), one nashsh twenty (dirhams), and one nawah five (dirhams)."
Explanation: According to the commentators, understanding these terms is essential for determining the nisab of zakah and the amount of the dowry (mahr), where one uqiyyah of silver is taken to mean forty dirhams.