Sahl b. Sa'd as-Sa'id reported that a person peeped through the hole of the door of Allah's Messenger (ﷺ), and at that time Allah's Messenger (ﷺ) had with him a scratching instrument with which he had been scratching his head. When Allah's Messenger (ﷺ) 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 (ﷺ) said: Permission is needed as a protection against glance.