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. (Using translation from Abū Dāʾūd 369)
أَنَّ النَّبِيَّ ﷺ صَلَّى وَعَلَيْهِ مِرْطٌ وَعَلَى بَعْضِ أَزْوَاجِهِ مِنْهُ وَهِيَ حَائِضٌ وَهُوَ يُصَلِّي وَهُوَ عَلَيْهِ