Musannaf Ibn Abi Shayba 3:456

Abu Bakr narrated to us, he said: Marwan bin Mu'awiyah narrated to us, from Isma'il bin Sami', from Malik bin 'Umayr, he said: Someone who saw Hudhayfah narrated to me that he was ill, and he was praying while a pillow had been placed for him, and a wooden board had been placed for him upon which he would prostrate.