From Sahih Muslim (Hadith 1500):
Anas b. Malik reported that the Messenger of Allah (ﷺ) wits the best among people in character. On occasions, the time of prayer would come while he was in our house. He would then order to spread the mat lying under him. That was dusted and then water was sprinkled over it. The Messenger of Allah (ﷺ) then led the prayer and we stood behind him, and that mat was made of the leaves of date-palm
Reference: Muslim 1500