The Prophet ﷺ prayed on a straw mat.
حدثنا وكيع حدثنا العمري عن إسحاق بن عبد الله بن أبي طلحة
أن النبي ﷺ صلى على حصير
No references are available.
Its isnad is sahih. Umari is Abdullah bin Umar bin Hafs bin Asim, and this has already appeared at 12280, where it is more complete.