Sahih Muslim , Book 7, Hadith 3098 (USC-MSA) ⓘ
'Abdullah b. Umar (Allah -be pleased with them) reported Allah's Apostle as saying: It is not lawful for a woman who believes in Allah and the Hereafter to travel for more than three nights journey except when there is a Mahram with her.
وَحَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا ابْنُ أَبِي فُدَيْكٍ، أَخْبَرَنَا الضَّحَّاكُ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " لاَ يَحِلُّ لاِمْرَأَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ تُسَافِرُ مَسِيرَةَ ثَلاَثِ لَيَالٍ إِلاَّ وَمَعَهَا ذُو مَحْرَمٍ " .
also referenced under: Book 15, Hadith 464 (In-Book) & Hadith 1338 (Reference)