(17) باب الاِسْتِئْذَانِ
It was narrated that Ali said:
"I had two times of visiting the Messenger of Allah(ﷺ), at night and during the day. If I came to him when he was praying, he would clear his throat (to let me know he was praying)."
Reference: Sunan Ibn Majah 3708
In-book reference: Book 33, Hadith 52
English translation: Vol. 5, Book 33, Hadith 3708