The Prophet ﷺ prayed on a sheet of cloth put on by one of his wives who was menstruating. He was praying while (a part of) it was upon him.
أَنَّ النَّبِيَّ ﷺ صَلَّى وَعَلَيْهِ مِرْطٌ وَعَلَى بَعْضِ أَزْوَاجِهِ مِنْهُ وَهِيَ حَائِضٌ وَهُوَ يُصَلِّي وَهُوَ عَلَيْهِ