The Book of the Prayer
2/2. Chapter:
The Time Of The Fajr Prayer
Sunan Ibn Majah
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.
Reference : Sunan Ibn Majah 669In-book reference : Book 2, Hadith 3English translation : Vol. 1, Book 2, Hadith 669