Hazrat Khalifatul-Masih V (may Allah be his Helper) said:
“It is narrated by Abu Raihana that he was with the Holy Prophet (peace and blessings of Allah be upon him) in a battle. One night he heard the Holy Prophet (peace and blessings of Allah be upon him) saying: ‘Fire is forbidden to touch the eye that remains awake for the sake of Allah and fire is forbidden on the eye that sheds tears for the fear of Allah.’ The same narration states that fire is forbidden on the eye that lowers its gaze instead of looking at that which is restricted by Allah. And fire is also forbidden to touch the eye that has been damaged in the way of Allah Almighty. [Sunan ad-Darimi, Kitab al-Jihad]
“Thus, when it is not permissible for men and women to look at each other with physical eyes, how can it be permissible to bring impure thoughts about one another into the mind? Therefore, the commandment to lower the gaze is for both men and women.
“Thus, consider how high is the status of doing ghadd-e-basar [lowering the eyes]; they are being included among those who worship Allah, strive in His path and are martyred. In other words, such people acquire this status because they keep their eyes lowered. People who follow this commandment will always be engaged in the worship of Allah and the ones to attain His nearness. …
“Mother of the Believers, Hazrat Umme Salamara related that she was with the Holy Prophet (peace and blessings of Allah be upon him), as was Hazrat Maimunahra when Ibn Umm-e-Maktumra came. This was after the commandment of purdah had been revealed. The Holy Prophet (peace and blessings of Allah be upon him) said: ‘Veil yourselves from him.’ We said, ‘Messenger of Allah, he is blind. He cannot see us or recognize us,’ whereupon the Holy Prophet (peace and blessings of Allah be upon him) said, ‘Are you both also blind and not seeing him?’ [Tirmidhi, Kitab al-Adab]
“Look at the sheer extent to which purdah is to be observed; not only are men commanded to lower their gaze, women too are commanded not to look at men unnecessarily.”
[Friday Sermon, January 30, 2004; Khutbat-e-Masroor, vol. 2, pp. 95–96; translated from Urdu]