Mukhtasar Bukhari

Narrated from Sayyiduna Sahl bin Sa’d (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) was scratching his head with a needle in his house, when a man peeped through a hole (which was in the wall of the house). The Prophet (peace be upon him) said: “If I had known that you were peeping, I would have poked this needle into your eye. O good man! Why has the command to seek permission been given? It is so that the gaze may not fall (unlawfully).”