It is narrated from Abu Sa'id Al-Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "There is no zakat on produce less than five wasq."
Hadith Referenceمسند الإمام الشافعي / كتاب الزكاة / 745
Hadith Takhrijاخرجه مسلم، الزكاة، باب ليس فيما دون خمسة أوسق صدقه (979)۔