Musannaf Ibn Abi Shayba 16:1005

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Shu’bah, from Sa’d ibn Ibrahim, from Sa’id ibn al-Musayyib, who said: The Messenger of Allah (may Allah bless him and grant him peace) cursed—or he said: May Allah make ugly—every red saddle.