'Narrated Abu Huraira: The Prophet (p.b.u.h) said, "It is not permissible for a woman who believes in Allah and the Last Day to travel for one day and night except with a Mahram." '
- (Sahih Bukhari: book-20, hadith-194)
'Narrated `Aisha: "A woman from the tribe of Bani Asad was sitting with me and Allah's Apostle (p.b.u.h) came to my house and said, "Who is this?" I said, "(She is) So and so. She does not sleep at night because she is engaged in prayer." The Prophet said disapprovingly: "Do (good) deeds which is within your capacity as Allah never gets tired of giving rewards till you get tired of doing good deeds." " '
- (Sahih Bukhari: book-21, hadith-251n)
(Image courtesy: siavash laghai)