Sahih Muslim 513
Sahih Muslim · Book 5: The Book of Mosques and Places of Prayer · It is permissible to offer voluntary prayers in congregation, and to pray on hasir (palm-fiber mats), khumrah (small mats), cloth, and other pure things
Maimuna, the wife of the Messenger of Allah (ﷺ), reported:
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ ، أَخْبَرَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ ، ح وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ ، قَالَ حَدَّثَنَا عَبَّادُ بْنُ الْعَوَّامِ ، كِلاَهُمَا عَنِ الشَّيْبَانِيِّ ، عَنْ عَبْدِ اللَّهِ بْنِ شَدَّادٍ ، قَالَ حَدَّثَتْنِي مَيْمُونَةُ ، زَوْجُ النَّبِيِّ صلى الله عليه وسلم قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي وَأَنَا حِذَاءَهُ وَرُبَّمَا أَصَابَنِي ثَوْبُهُ إِذَا سَجَدَ وَكَانَ يُصَلِّي عَلَى خُمْرَةٍ .
The Messenger of Allah (ﷺ) said prayer while I was by his side, and at times when he prostrated his cloth touched me, and he prayed on a small mat.