Messenger of Allah, ask your ladies to observe veil, but Messenger of Allah ﷺ did not do that. So there went out Sauda, daughter of Zarn'a, the wife of Messenger of Allah ﷺ, during one of the nights when it was dark. She was a tall statured lady. 'Umar called her saying: Sauda, we recognise you. (He did this with the hope that the verses pertaining to veil would be revealed.) 'A'isha said: Allah, the Exalted and Glorious, then revealed the verses pertaining to veil. (Using translation from Muslim 2170d)
أَنَّ أَزْوَاجَ النَّبِيِّ ﷺ كُنَّ يَخْرُجْنَ بِاللَّيْلِ إِذَا تَبَرَّزْنَ إِلَى الْمَنَاصِعِ وَهُوَ صَعِيدٌ أَفْيَحُ وَكَانَ عُمَرُ بْنُ الْخَطَّابِ يَقُولُ لِرَسُولِ اللهِ ﷺ احْجُبْ نِسَاءَكَ فَلَمْ يَكُنْ رَسُولُ اللهِ ﷺ يَفْعَلُ فَخَرَجَتْ سَوْدَةُ بِنْتُ زَمْعَةَ زَوْجُ النَّبِيِّ ﷺ لَيْلَةً مِنَ اللَّيَالِي عِشَاءً وَكَانَتْ امْرَأَةً طَوِيلَةً فَنَادَاهَا عُمَرُ أَلَا قَدْ عَرَفْنَاكِ يَا سَوْدَةُ حِرْصًا عَلَى أَنْ يُنْزَلَ الْحِجَابُ قَالَتْ عَائِشَةُ فَأُنْزِلَ الْحِجَابُ