Reference: Fataawa Ramadhaan – Volume 2, Page 903, Fatwa No.886
Fataawa as-Siyaam libni Jibreen – Page 185
Question: What is the basis for the legislation of Zakaatul-Fitr?
Response: The basis for it being legislated are the authentic ahaadeeth of the Prophet ﷺ. Such as the hadeeth of ‘Abdullaah Ibn ‘Umar (radhi-yAllaahu ‘anhumaa) who said: “The Prophet ﷺ legislated Sadaqatul-Fitr – or he said Ramadhaan – upon the male and the female, the free [person] and the slave a saa’ of dates (one saa’ is equal to four mudd, and one mudd is equal to the amount held by cupping the two hands together. It is a measure by volume and not by weight)…”, [and] the hadeeth [goes on].
And some of the scholars have deduced it being legislated by the statement of Allaah (subhaanahu wa-ta’aala):
{Indeed whosoever purifies himself shall achieve success}, [Soorah al-A’laa, Aayah 14].
So they have expounded {purifies himself} to [mean] Zakaatul-Fitr.
