The Prophet (ﷺ) said: A man's messenger sent to another indicates his permission to enter.
Sunan Abi Dawud Book 43, Hadith 417
← Previous Hadith I went out with the (Messenger of Allah (ﷺ) until I entered a garden, he said: Keep on closing the door. The door was then closed. I then said: Who is there ? He then narrated the rest of the tradition.

Abu Dawud said: That is to say, the tradition of Abu Musa al-Ash'ari. In this version he said: "He then knocked at the door."

Sunan Abi Dawud Book 43, Hadith 416 Next Hadith → The Prophet (ﷺ) said: When one of you is invited to take meals and comes along with the messenger, that serves as permission for him to enter.

Abu 'Ali al-Lu'lu said: I heard Abu Dawud say: Qatadah did not hear anything from Abu Rafi'.

Sunan Abi Dawud Book 43, Hadith 418