Abu Sa'id Al-Khudri (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "There is no zakat on produce less than five wasq."
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 744
Hadith Takhrijاخرجه البخارى الزكاة، باب زكاة الورق (1447)۔