Musnad Ahmad Hadith 13478

It is narrated from Anas (may Allah be pleased with him) that when the command of veiling (purdah) was revealed, I know the circumstances of that time better than anyone else. That night, the Prophet (ﷺ) was in seclusion with Zainab (may Allah be pleased with her), and in the morning the Prophet (ﷺ) was a bridegroom. After that, the Prophet (ﷺ) invited the people, they came, ate food, and left, but some people remained sitting there and continued to sit for quite a while, until the Prophet (ﷺ) himself got up and went outside. I also went outside so that they might leave as well. The Prophet (ﷺ) and I, while walking, stopped at the threshold of Aisha’s (may Allah be pleased with her) chamber. The Prophet (ﷺ) thought that perhaps those people had now left, so the Prophet (ﷺ) returned, and I was with him, but those people were still sitting there. The same thing happened again, but this time those people had actually left. Then the Prophet (ﷺ) entered inside and hung a curtain, and Allah revealed the verse of hijab.