Sahih Muslim , Book 7, Hadith 3096 (USC-MSA) ⓘ
Ibn Umar (Allah be pleased with them) reported Allah's Messenger as saying: A woman should not set out on three (days' journey) except when she has a Mahram with her.
حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، قَالاَ حَدَّثَنَا يَحْيَى، - وَهُوَ الْقَطَّانُ - عَنْ عُبَيْدِ اللَّهِ، أَخْبَرَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ تُسَافِرِ الْمَرْأَةُ ثَلاَثًا إِلاَّ وَمَعَهَا ذُو مَحْرَمٍ " .
also referenced under: Book 15, Hadith 462 (In-Book) & Hadith 1338 (Reference)