Musannaf Ibn Abi Shayba 28:282

Waki’ narrated to us, he said: Sufyan narrated to us, from Qays ibn Muslim, from ‘Abd al-Rahman ibn Abi Layla, he said: Sa’d ibn ‘Ubayd al-Qari said on the day of al-Qadisiyyah: "We are meeting the enemy tomorrow, if Allah wills, and we will be martyred. So do not wash any blood from us, and do not shroud us except in the garment that was upon us."