Language:
كتاب التقصير
18  
Shortening the Prayers (At-Taqseer)
(4)
Chapter: The length of the journey that makes it permissible to offer a shortened prayer?
(4)
باب فِي كَمْ يَقْصُرُ الصَّلاَةَ
Sahih al-Bukhari 1086

Narrated Ibn `Umar:

The Prophet (ﷺ) said, "A woman should not travel for more than three days except with a Dhi-Mahram (i.e. a male with whom she cannot marry at all, e.g. her brother, father, grandfather, etc.) or her own husband.)"

حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ الْحَنْظَلِيُّ، قَالَ قُلْتُ لأَبِي أُسَامَةَ حَدَّثَكُمْ عُبَيْدُ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ ‏ "‏ لاَ تُسَافِرِ الْمَرْأَةُ ثَلاَثَةَ أَيَّامٍ إِلاَّ مَعَ ذِي مَحْرَمٍ ‏"‏‏.‏
Reference : Sahih al-Bukhari 1086
In-book reference : Book 18, Hadith 7
USC-MSA web (English) reference : Vol. 2, Book 20, Hadith 192
  (deprecated numbering scheme)