Zayd bin Aslam زيد بن أسلم · The Book on Zakat

the Messenger of Allah said: "Whoever acquired wealth, then there is no Zakat on it until the Hawl has passed (while it is in his possession)."

"We would give Zakat Al-Fitr - when the Messenger of Allah was among us - as a Sa of food, or a Sa of barely, or a Sa of dried dates, or a Sa of raisins, or a Sa of cheese. So we did not stop paying it (like that) until Mu'awiyah arrived in Al-Madinah and talked (about it). Among the things he addressed the people with, he said: 'I see that two Mudd of the wheat of Ash-Sham are…