Ayyad bin 'Abdullah bin Sa'd عياض بن عبد الله بن سعد بن أبي سرح · The Book on Zakat

"During the time of the Messenger of Allah, a man suffered a loss on fruits that he had sold, resulting in more debt. The Messenger of Allah said: 'Give him charity.' So the people gave him charity but it did not cover his debt. So the Messenger of Allah said to his debtors: 'Take what you have and there is nothing for you but that.'"

"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…