Sahih Muslim 2281
صحيح مسلم#2281SahihAbdullah b. Umar reported that the Messenger of Allah (ﷺ) ordered the (payment of) Zakat-ul-Fitr one sa' of dates, or one sa' of barley. Ibn 'Umar ('Abdullah b. 'Umar) further said:The people equalised it (then) with two mudds of fine wheat
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 12:19