An-Nur · 24:60

60. And the elderly women that no longer experience menstruation, or can no longer give birth, nor have any desire to marry again, there is no sin upon them if they do not wear some of their outer garments i.e. overcloak and veil, as long as they do not expose the beauty they have been commanded to conceal. However, for them to wear those garments is better for them than to discard them, enhancing veiling and chastity. Allah is all-hearing of your statements; none of them are hidden from Him and He shall requit you for them.