Mukhtasar Muslim

Narrated from Sayyiduna Sahl bin Sa’d Sa’idi (may Allah be pleased with him) that a man peeped through a hole in the door of the Messenger of Allah (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) had an iron tool (comb) in his hand, with which he was scratching his head. When the Prophet (peace and blessings be upon him) saw him, he said: “If I had known that you were looking at me, I would have poked your eye.” And the Prophet (peace and blessings be upon him) said: “Permission (to enter) has been prescribed only to protect the eye (i.e., from peeping into someone else’s house, and this is forbidden).”