Sahih
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ كُنَّ نِسَاءُ الْمُؤْمِنَاتِ يُصَلِّينَ مَعَ النَّبِيِّ ـ صلى الله عليه وسلم ـ صَلاَةَ الصُّبْحِ ثُمَّ يَرْجِعْنَ إِلَى أَهْلِهِنَّ فَلاَ يَعْرِفُهُنَّ أَحَدٌ . تَعْنِي مِنَ الْغَلَسِ .
It was narrated that 'Aishah said:"The believing women used to perform the Subh prayer with the Prophet, then they would go back to their families and no one would recognize them," meaning of the darkness