It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him), though Zuhayr (may Allah have mercy on him) said: I think he narrated it from the Messenger of Allah (peace and blessings be upon him), that he (peace and blessings be upon him) said: "Bring a quarter of a tenth, that is, one dirham out of every forty dirhams; but nothing (of zakah) is due on you until they reach two hundred dirhams. When they reach two hundred dirhams, five dirhams must be paid from them. And whatever more there is, zakah will be paid at the same rate."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7521
Nafi' (may Allah have mercy on him) narrates from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both): "Whatever amount exceeds that, its zakah will be paid at the same rate."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7522
Abd al-Rahman bin Abi al-Zinad narrates that his father (Abu al-Zinad, may Allah have mercy on him) said: Among the jurists of ours whom I met and whose word was final were Sa'id bin al-Musayyib, Urwah bin al-Zubayr, al-Qasim bin Muhammad, Abu Bakr bin Abd al-Rahman, Kharijah bin Zayd bin Thabit, Ubaydullah bin Abdullah bin Utbah and Sulayman bin Yasar, among other eminent elders besides them. Sometimes they differed on a matter, and we would take the view of the majority of them and those best in judgement. Then he mentioned some rulings and said: They used to say: There is no zakah on dates or on grain until the estimate of the dates or the measure of the grain reaches five wasqs by the sa' of the Prophet (peace and blessings be upon him). They did not hold zakah to be due on any fruits except grapes, when their estimate reaches five wasqs by the sa' of the Prophet (peace and blessings be upon him). They held that zakah is due on every amount in excess (of the threshold) of gold, silver, dates, grain and grapes, even if it exceeds by one mudd, or more, or less. And they did not hold zakah to be due on the excess of livestock: camels, cattle and sheep.
It is reported from Ibrahim al-Nakha'i (may Allah have mercy on him) that whatever exceeds two hundred, zakah will be due on it at the same rate.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7523