Ash-Shama'il Al-Muhammadiyah, Book 46, Hadith 328 (In-Book)

'Aayeshah Radiyallahu 'Anha reports that the bed on which Rasulullah Sallallahu 'Alayhi Wasallam slept was made of leather, in which was filled coir of the palm tree.

حَدَّثَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ‏:‏ حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَ‏:‏ إِنَّمَا كَانَ فِرَاشُ رَسُولِ اللهِ صلى الله عليه وسلم، الَّذِي يَنَامُ عَلَيْهِ مِنْ أَدَمٍ، حَشْوُهُ لِيفٌ‏.‏

also referenced under: Book 45, Hadith 311 (English)