Musnad Abu Ya'la al-Mawsili 149:48

Surayj ibn Yunus narrated to us, Abu Mu'awiyah narrated to us, from Hisham ibn 'Urwah, from 'Urwah, from 'Aishah, who said: The bedding of the Messenger of Allah, peace and blessings of Allah be upon him, upon which he would sleep at night, was made of leather stuffed with palm fiber.