It is narrated from Sayyiduna Mu'awiyah (may Allah be pleased with him): I heard the Messenger of Allah (peace and blessings be upon him) say: "Do not ride on silk (khazz) or on leopard skins."
(b) (The prohibition of) silk will be taken as tanzihi (discouraged, not forbidden); its evidence will come in the Book of Prayer, in sha Allah.
(c) Abu Shaykh al-Huna'i narrated the like from Sayyiduna Mu'awiyah (may Allah be pleased with him) concerning leopard skins.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 75