The Messenger of Allah (ﷺ) commanded us to bring out the secluded women on the day of 'Id (festival). He was asked: What about the menstruous women ? He said: They should be present at the place of virtue and the supplications of the Muslims. A woman said: Messenger of Allah, what should we do it one of us does not possess an outer garment ? He replied: Let her friend lend a part of her garment.
Sunan Abi Dawud Book 2, Hadith 747