The Book on General Behaviour (Kitab Al-Adab)

Muslim :: Book 25 : Hadith 5366

Sahl b. Sa'd as-Sa'id reported that a person peeped through the hole of the door of Allah's Messenger (may peace be upon him), and at that time Allah's Messenger (may peace be upon him) had with him a scratching instrument with which he had been scratching his head. When Allah's Messenger (may peace be upon him) saw him. he said: If I were to know that you had been peeping through the door, I would have thrust that into your eyes, and Allah's Messenger (may peace be upon him) said: Permission is needed as a protection against glance.