Sahih al-Bukhari 1506
صحيح البخاري#1506SahihNarrated Abu Sa`id Al-Khudri:We used to give one Sa' of meal or one Sa' of barley or one Sa' of dates, or one Sa' of cottage cheese or one Sa' of Raisins (dried grapes) as Zakat-ul-Fitr
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 24:106