Yahya bin Ayoub al-Maqabri يحيى بن أيوب المقابري · General Behavior (Kitab Al-Adab)

When the Messenger of Allah (ﷺ) came to some people's door, he did not face it squarely, but faced the right or left corner, and said: Peace be upon you! peace be upon you! That was because there were no curtains on the doors of the house at that time.