(5) The Book of Greetings
كتاب السلام
(132) Chapter: Words to be Used for Offering Greetings
(132) - باب كيفية السلام
Riyad as-Salihin 853 
Al-Miqdad (May Allah be pleased with him) reported in a long Hadith:
We used to reserve for the Prophet (ﷺ) his share of the milk, and he would come at night and offer greetings in such a manner as did not disturb those asleep and was heard only by those who were awake. In fact, the Prophet (ﷺ) came and offered greetings as usual.

[Muslim].

وعن المقداد رضي الله عنه في حديثه الطويل قال‏:‏ كنا نرفع للنبي صلى الله عليه وسلم نصيبه من اللبن، فيجيء من الليل، فيسلم تسليمًا لا يوقظ نائمًا، ويسمع اليقظان، فجاء النبي صلى الله عليه وسلم فسلم كما كان يُسلم‏.‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏
Reference : Riyad as-Salihin 853
In-book reference : Book 5, Hadith 10