Sahih al-Bukhari Book 65, Hadith 313
When Allah's Messenger (ﷺ) married Zainab bint Jahsh, he invited the people to a meal. They took the meal
and remained sitting and talking. Then the Prophet (showed them) as if he is ready to get up, yet they
did not get up. When he noticed that (there was no response to his movement), he got up, and the
others too, got up except three persons who kept on sitting. The Prophet (ﷺ) came back in order to enter
his house, but he went away again. Then they left, whereupon I set out and went to the Prophet (ﷺ) to tell
him that they had departed, so he came and entered his house. I wanted to enter along with him, but he
put a screen between me and him. Then Allah revealed:
'O you who believe! Do not enter the houses of the Prophet...' (33.53)
I said, "O Allah's Messenger (ﷺ)! Good and bad persons enter upon you, so I suggest that you order the mothers of the Believers (i.e. your wives) to observe veils." Then Allah revealed the Verses of Al- Hijab.
I of all the people know best this verse of Al-Hijab. When Allah's Messenger (ﷺ) married Zainab bint Jahsh she was with him in the house and he prepared a meal and invited the people (to it). They sat down (after finishing their meal) and started chatting. So the Prophet (ﷺ) went out and then returned several times while they were still sitting and talking. So Allah revealed the Verse: 'O you who believe! Enter not the Prophet's houses until leave is given to you for a meal, (and then) not (so early as) to wait for its preparation .....ask them from behind a screen.' (33.53) So the screen was set up and the people went away.