Mishkat al-Masabih #1353

Umm ‘Atiya said: We were commanded to bring out the men-struous women and those who were secluded on the day of the two festivals so that they might be present at the congregational prayer of the Muslims and their supplication, but the menstruous women had to keep at a distance from their place of prayer. A woman said, “Messenger of God, one of our number does not possess an outer garment." He replied, “Let her friend lend her hers." (Bukhari and Muslim.)