The Messenger of Allah ﷺ said, "I have exempted horses and slaves from zakat, so bring the zakat on silver, one dirham for every forty dirhams. Nothing is due on one hundred and ninety, but when it reaches two hundred, then five dirhams are due on it."
حدثنا عمرو بن عون أخبرنا أبو عوانة عن أبي إسحق عن عاصم بن ضمرة
قال رسول الله ﷺ قد عفوت عن الخيل والرقيق فهاتوا صدقة الرقة من كل أربعين درهما درهما وليس في تسعين ومائة شيء فإذا بلغت مائتين ففيها خمسة دراهم
Its isnad is daif. Tirmidhi transmitted it in the Book of zakat, chapter on what has been said regarding zakat on gold and silver, no. 620, from the hadith of Abu Awana with this chain. Ibn Khuzayma graded it sahih, no. 2284, and Baghawi graded it hasan in Sharh al-Sunnah, 6/47. The hadith has many corroborating narrations.Abu Ishaq used ambiguous transmission wording (anana).