Musannaf Ibn Abi Shayba 3:397

Abu Bakr narrated to us, he said: Zayd ibn al-Hubab narrated to us, from Hisham ibn Sa'd, from Zayd ibn Aslam, he said: I said to 'Ata' ibn Yasar: "Do I prostrate upon my garment?" He said: "My garments are part of me."