Sahih Al Bukhari Hadith Number 872

Narrated `Aisha: Allah’s Messenger (peace be upon him) used to offer the Fajr prayer when it was still dark and the believing women used to return (after finishing their prayer) and nobody could recognize them owing to darkness, or they could not recognize one another.

10  Call to Prayers (Adhaan)
Hadith number 872
Volume no 1
Chapter: 165 ( Returning of the women immediately after the Fajr prayer and their staying in the mosque for a short period only)