It is narrated from Sayyiduna Abu Rafi' (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) sent a man from Banu Makhzum to collect the zakah, and the Messenger of Allah (peace and blessings be upon him) said: "There is no zakah on grain less than five wasqs, there is no zakah on less than five camels, and there is no zakah on silver less than five uqiyahs."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 929