(17) باب التَّنَحْنُحِ فِي الصَّلاَةِ
It was narrated that 'Ali said:
"I had two times when I would enter upon the Messenger of Allah (ﷺ), one at night and one during the day. When I entered at night he would clear his throat (to tell me to come in)."
Reference: Sunan an-Nasa'i 1212
In-book reference: Book 13, Hadith 34
English translation: Vol. 2, Book 13, Hadith 1213