Ibn Abbas (RA) has narrated that Rasûlullâh SAW prescribed Sadaqatul Fitr as an obligatory duty in order to purify those who fast, from useless and obscene activities and to provide food for the poor. (Abu Dawood)

Sadaqatul Fitr has been stipulated by Rasulullah (SAW) in authentic Ahadith.  The Sahabah (RA) and later the Jurists adapted the stipulations according to the needs of the time.

Abdullah Ibn Umar RA is reported to have said; “Rasulullah (SAW) instructed us to give Sadaqatul Fitr, 1 Sa’ (a measure used at the time of Rasulullah SAW) of dates or 1 Sa’ of barley.  Abdullâh Ibn Umar RA mentions that the Sahabâh (RA) later gave 2 Mud (½ Sa’) of wheat in place of dates and barley.

(Bukhari 1511 and Muslim 7232)