Sunnah.com reference : Book 4, Hadith 8English translation : Book 4, Hadith 629Arabic reference : Book 4, Hadith 605
Ali (RAA) narrated that the Messenger of Allah (ﷺ) said:
“When you possess two hundred Dirhams at the end of the year (if you still have all of them), five Dirhams are levied on them as Zakah. There is nothing upon you (to be paid) in gold, until it reaches (the value of) twenty Dinars. When you possess twenty Dinars, at the end of the year, then there is half a Dinar levied on it (as Zakah). Any additional amount will be calculated in the same manner. No Zakah is to be paid on monetary holdings, until they have been owned for one year.” Related by Abu Dawud, who rendered it Hasan.
وَعَنْ عَلِيٍّ ‏- رضى الله عنه ‏- قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ إِذَا كَانَتْ لَكَ مِائَتَا دِرْهَمٍ ‏-وَحَالَ عَلَيْهَا اَلْحَوْلُ‏- فَفِيهَا خَمْسَةُ دَرَاهِمَ, وَلَيْسَ عَلَيْكَ شَيْءٌ حَتَّى يَكُونَ لَكَ عِشْرُونَ دِينَارًا, وَحَالَ عَلَيْهَا اَلْحَوْلُ, فَفِيهَا نِصْفُ دِينَارٍ, فَمَا زَادَ فَبِحِسَابِ ذَلِكَ, وَلَيْسَ فِي مَالٍ زَكَاةٌ حَتَّى يَحُولَ عَلَيْهِ اَلْحَوْلُ }  رَوَاهُ أَبُو دَاوُدَ, وَهُوَ حَسَنٌ, وَقَدِ اِخْتُلِفَ فِي رَفْعِه ِ  1‏ .‏‏1 ‏- صحيح.‏ رواه أبو داود ( 1573 )‏، وإن كان الدارقطني أعله بالوقف، فلقد صححه البخاري.‏