Hadithcore
Sunan Abi Dawud, 658
sahih· Al-Albani

Anas b. Malik said; the prophet (ﷺ) used to visit Umm Sulaim. Sometimes the time for prayer would come and he would pray on out carpet that was really a mat. She (Umm Sulaim) used to wash it with water.

حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا الْمُثَنَّى بْنُ سَعِيدٍ الذَّرَّاعُ، حَدَّثَنَا قَتَادَةُ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَزُورُ أُمَّ سُلَيْمٍ فَتُدْرِكُهُ الصَّلاَةُ أَحْيَانًا فَيُصَلِّي عَلَى بِسَاطٍ لَنَا وَهُوَ حَصِيرٌ نَنْضَحُهُ بِالْمَاءِ ‏.‏

References2 variants
In-Book Reference
Book 2, Hadith 268
English Reference
Book 2, Hadith 658