Do not look into peoples homes or enter them without permission

O you who have believed, do not enter houses other than your own houses until you ascertain welcome and greet their inhabitants. That is best for you; perhaps you will be reminded.

[Qur'aan 24:27]

It was narrated from Sahl bin Sa'd As-Saidi that a man looked through a hole in the door of the Prophet, who had with him a kind of comb with which he was scratching his head. 

When the Messenger of Allah saw him he said: "If I had known that you were watching me, I would have stabbed you in the eye with this. 

This rule of asking permission has been ordained so that one may not look unlawfully (into people's houses).

[Sunan al-Nasaa'i, Sahih al-Bukhaari, and Sahih Muslim]

What a heinous crime it is to look into someone's house without permission. Do you not read that the Messenger of Allaah (sallallaahu alayhi wa sallam) said: "If I had known that you were watching me, I would have stabbed you in the eye with this?"

This is just for looking into a house without the permission of the owner. Imagine how horrible the act of breaking into someone's house must be in front of Allaah.

A mess of a translation

This hadith has been mistranslated at Sunnah.com here. It has been translated correctly at other places on the website. However, in the link mentioned the author [from whom the website took the translation] seems to have made a complete mess. 

For starters the chapter heading has been mistranslated 

بَابُ الاسْتِئْذَانُ مِنْ أَجْلِ النَّظَرِ

The author translated it as:

Asking permission without looking

That is incorrect. The correct translation is:

Asking permission was a result [i.e. it had been prescribed because of] the sight

Second, the author translated the hadiith as:

إِنَّمَا جُعِلَ الإِذْنُ مِنْ أَجْلِ الْبَصَرِ‏

"The ear is put in the place of the eye."

The Hadiith has nothing to do with the ear!!! Instead, the correct translation is:

Seeking permission has been prescribed because of the sight [i.e. in order to protect against a person looking into the house at something he was not supposed to].

This highlights why one needs to be careful when reading translated material.