ENOfficial
Maimunah bint al-Harith reported : the Messenger of Allah (ﷺ) used to pray while. I was by his side in the state of menstruation. Sometime his cloth would touch me when he prostrated. He would pray on a small mat.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَمْرُو بْنُ عَوْنٍ، حَدَّثَنَا خَالِدٌ، عَنِ الشَّيْبَانِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ شَدَّادٍ، حَدَّثَتْنِي مَيْمُونَةُ بِنْتُ الْحَارِثِ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي وَأَنَا حِذَاءَهُ وَأَنَا حَائِضٌ وَرُبَّمَا أَصَابَنِي ثَوْبُهُ إِذَا سَجَدَ وَكَانَ يُصَلِّي عَلَى الْخُمْرَةِ .
sunnah.com