It is narrated from Sayyiduna Abu Musa Ash'ari, may Allah be pleased with him, that indeed the Messenger of Allah, peace and blessings be upon him, said: "Every eye is an adulterer."
Explanation: In this blessed hadith, there is an indication towards safeguarding the gaze. Every eye is adulterous, meaning every eye that looks at a non-mahram with desire, because the eye is the gateway to a person’s heart, and the beginning of all lustful temptations generally starts with the eye. First comes the glance, then a smile, then greeting, then conversation, then a promise, and then the matter reaches to a meeting. That is why Allah Ta‘ala has commanded His believing servants:
“Say to the believing men that they should lower their gaze and guard their private parts; that is purer for them. Surely Allah is well aware of what they do. And say to the believing women that they should lower their gaze and guard their private parts.”