38. The Book of Manners and Etiquette - كتاب الآداب
9) Chapter: The Prohibition Of Looking Into A House
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
If a person were to cast a glance in your (house) without permission, and you had in your hand a staff and you would have thrust that in his eyes, there is no harm for you.