Sufyan, narrating with his full chain, says that the Prophet (peace and blessings be upon him) said: "There is no zakah on grain or dates until they reach five wasqs, nor is there zakah on less than five camels, nor is there zakah on less than five uqiyahs of silver."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7470