Musannaf Ibn Abi Shaybah

Imam Zuhri states that regarding the leaders of this Ummah who were in Madinah—Abu Bakr, Umar, and Uthman—we have not received any report that they collected zakat twice in a year. However, every year they used to send (people) for both green and dry produce so that it would be collected from them according to the Sunnah of the Messenger (peace and blessings be upon him).