From Sahih Muslim (Hadith 5443):
Abu Burda reported that A'isha brought out for us the lower garment and the upper garment made of the Mulabbada cloth and said:It was in these (clothes) that Allah's Messenger (ﷺ) died. Ibn Hatim (one of the narrators) in his narration Wd: The lower garment of coarse cloth
Reference: Muslim 5443