Musannaf Ibn Abi Shayba 28:280

Waki’ narrated to us, he said: Sufyan narrated to us, from Makhul ibn Rashid al-Nahdi, from al-Izar ibn Hurayth al-‘Abdi, he said: Zayd ibn Suhan said on the Day of the Camel: "Bury me in the earth, a burial, and do not wash any blood from me, and do not remove any garment from me, except for the leather socks (khuffayn), for I am a disputant who will dispute."