Sayyiduna Sa'd bin Abi Dhubab (may Allah be pleased with him) says: I came to the Messenger of Allah (peace and blessings be upon him) and accepted Islam. Then I said: "O Messenger of Allah, write (a document) for those of my people who have accepted Islam concerning their properties." So he (peace and blessings be upon him) wrote it and appointed me as governor over them. Then Abu Bakr (may Allah be pleased with him), and then Umar (may Allah be pleased with him), appointed me as governor. Sa'd (may Allah be pleased with him) was from the people of al-Sarat. He says: I spoke to my people about honey and said to them that there is zakah on it, for there is no good in produce on which zakah is not paid. They said: How much zakah? I said: "A tenth." So I collected the tithe from them, and I came to Umar bin al-Khattab (may Allah be pleased with him) and informed him of it. Umar (may Allah be pleased with him) took it and sold it, and then put its price into the treasury of the Muslims.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7462