Sahih al-Bukhari 1507
صحيح البخاري#1507SahihNarrated `Abdullah bin `Umar:The Prophet (ﷺ) ordered (Muslims) to give one Sa' of dates or one Sa' of barley as Zakat-ul-Fitr. The people regarded two Mudds of wheat as equal to that
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: 24:107