Musnad Abu Ya'la al-Mawsili 149:92

Abu Bakr narrated to us, Yazid ibn al-Miqdam narrated to us, from al-Miqdam ibn Shurayh, from his father, that he asked Aisha: "Did the Messenger of Allah pray on a mat? For I heard in the Book of Allah: 'And We have made Hell a mat (hasiran) for the disbelievers' (referring to the commanders)." She said: "He did not pray on it."