"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)."
Sunan an-Nasa'i Book 13, Hadith 34
← Previous Hadith "I had certain times when I used to come to the Messenger of Allah (ﷺ). When I came to him I would ask for permission to enter. If I found him praying he would clear his throat and I would enter, and if I found him free he would give me permission (to enter)."

Sunan an-Nasa'i Book 13, Hadith 33 Next Hadith → "Ali said to me: 'I was so close to the Messenger of Allah (ﷺ), closer than anyone else. I used to come to him at the end of every night, before dawn, and say: "As-salamu 'alayka ya Nabiyy Allah (Peace be upon you, O Prophet of Allah)." If he cleared his throat I would go back to my family, otherwise I would enter upon him.'"

Sunan an-Nasa'i Book 13, Hadith 35