Dress

Bukhari :: Book 7 :: Volume 72 :: Hadith 807

Narrated Sa'd:

A man peeped into the house of the Prophet through a hole while the Prophet was scratching his head with a Midrai (a certain kind of comb). On that the Prophet said (to him), "If I had known you had been looking, then I would have pierced your eye with that instrument, because the asking of permission has been ordained so that one would not see things unlawfully."