Sahih Muslim , Book 7, Hadith 3104 (USC-MSA) ⓘ
Abu Huraira (Allah be pleased with him) reported Allah's Messenger as saying: It is not lawful for a Muslim woman to travel a night's journey except when there is a Mahram with her.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا لَيْثٌ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ، عَنْ أَبِيهِ، أَنَّ أَبَا هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ يَحِلُّ لاِمْرَأَةٍ مُسْلِمَةٍ تُسَافِرُ مَسِيرَةَ لَيْلَةٍ إِلاَّ وَمَعَهَا رَجُلٌ ذُو حُرْمَةٍ مِنْهَا " .
also referenced under: Book 15, Hadith 470 (In-Book) & Hadith 1339 (Reference)