Whenever the Messenger of Allah ﷺ came to someone's door, he would not stand directly facing it, but would position himself to its right or left side, saying, "Peace be upon you, peace be upon you." This was because in those days the houses did not have curtains over their doorways.
كان رسول الله ﷺ إذا أتى باب قوم لم يستقبل الباب من تلقاء وجهه، ولكن من ركنه الأيمن، أو الأيسر، ويقول: السلام عليكم، السلام عليكم وذلك أن الدور لم يكن عليها يومئذ ستور.
Reported by Abu Dawud (5186), Ahmad (17694), and Bukhari in Adab al-Mufrad (1078), all of them via the route of Baqiya bin Walid, who said, "Muhammad bin Abdul-Rahman narrated to us, from Abdullah bin Busr," who said, and then he related it.Its chain of transmission is hasan because of Baqiya bin Walid, for his narration is hasan when he explicitly states that he heard it directly, and he did state this explicitly in this hadith. It has also been corroborated. Ahmad (17692) reported it via the route of Ismail bin Ayyash, and Bayhaqi in Shuab (8437) reported it via the route of Uthman bin Saeed bin Kathir, and also via the route of Yahya bin Saeed Attar (8438). All three of them narrated it from Muhammad bin Abdul-Rahman in a similar manner.