Musannaf Ibn Abi Shayba 5:252

Safwan ibn Isa narrated to us, from al-Harith ibn Abd al-Rahman, from Munir ibn Abd Allah, from his father, from Sa’d ibn Abi Dhubab, that he came to his people and said to them: "There is Zakat in honey, for there is no good in wealth that is not purified (by Zakat)." He said: They asked, "How much do you see (is due)?" I said, "One-tenth." So he took one-tenth from them and brought it to Umar and informed him about it. He said: Umar took it and placed it among the charities of the Muslims.