The Messenger of Allah ﷺ commanded that the zakat al-fitr be given as a saa of dates, a saa of barley, or a saa of unhusked barley.
حدثنا هشام بن عمار حدثنا عبد الرحمن بن سعد بن عمار المؤذن حدثنا عمر بن حفص
أن رسول الله ﷺ أمر بصدقة الفطر صاعا من تمر أو صاعا من شعير أو صاعا من سلت
[Sahih], see hadith no: 1101 for its defect. Umar bin Hafs has some weakness in him, from the seventh generation (Taqrib), and Ammar bin Saad is a tabii whose condition is unknown, but it has sahih corroborating narrations.