Mustaqim bin Abd al-Malik said: "I saw on Sayyiduna al-Hasan and Sayyiduna al-Husayn (may Allah be pleased with them both) upstanding socks of khazz (a silk-blend fabric), and I saw them riding trade-bred horses (baradhin)."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2781