Sahih Bukhari 146

حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ ، قَالَ : حَدَّثَنَا اللَّيْثُ ، قَالَ : حَدَّثَنِي عُقَيْلٌ ، عَنِ ابْنِ شِهَابٍ ، عَنْ عُرْوَةَ ، عَنْ عَائِشَةَ ، أَنَّ أَزْوَاجَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كُنَّ يَخْرُجْنَ بِاللَّيْلِ إِذَا تَبَرَّزْنَ إِلَى الْمَنَاصِعِ وَهُوَ صَعِيدٌ أَفْيَحُ ، فَكَانَ عُمَرُ يَقُولُ لِلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : احْجُبْ نِسَاءَكَ ، فَلَمْ يَكُنْ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَفْعَلُ ، فَخَرَجَتْ سَوْدَةُ بِنْتُ زَمْعَةَ زَوْجُ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَيْلَةً مِنَ اللَّيَالِي عِشَاءً ، وَكَانَتِ امْرَأَةً طَوِيلَةً ، فَنَادَاهَا عُمَرُ : أَلَا قَدْ عَرَفْنَاكِ يَا سَوْدَةُ حِرْصًا عَلَى أَنْ يَنْزِلَ الْحِجَابُ ، فَأَنْزَلَ اللَّهُ آيَةَ الْحِجَابِ .

Narrated `Aisha: The wives of the Prophet used to go to Al-Manasi, a vast open place (near Baqi` at Medina) to answer the call of nature at night. `Umar used to say to the Prophet Let your wives be veiled, but Allah's Apostle did not do so. One night Sauda bint Zam`a the wife of the Prophet went out at `Isha' time and she was a tall lady. `Umar addressed her and said, I have recognized you, O Sauda. He said so, as he desired eagerly that the verses of Al-Hijab (the observing of veils by the Muslim women) may be revealed. So Allah revealed the verses of Al-Hijab (A complete body cover excluding the eyes).