Muwatta Malik, Book 54, Hadith 1803 (In-Book) ⓘ

Malik related to me from Said ibn Abi Said al-Maqburi from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "It is not halal for a woman who believes in Allah and the Last Day to travel the distance of a day and night without a man who is her mahram."

وَحَدَّثَنِي مَالِكٌ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ لاَ يَحِلُّ لاِمْرَأَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخَرِ تُسَافِرُ مَسِيرَةَ يَوْمٍ وَلَيْلَةٍ إِلاَّ مَعَ ذِي مَحْرَمٍ مِنْهَا ‏" ‏ ‏.‏