Jami` at-Tirmidhi 620
جامع الترمذي#620Da'ifAli narrated that :the Messenger of Allah said: "I have exempted charity on horses and slaves. So bring charity for silver, one Dirham for every forty Dirham. There is nothing for me (to collect) on one hundred and ninety Dirham, so when it reaches two hundred, then five Dirham of it (are due)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufSahih
Zubair Ali ZaiDaif
In-book reference: 7:4