Hadithcore
Sahih Muslim, 827 e
sahih

Qaza'ah reported:

I heard Abu Sa'id al-Khudri (Allah be pleased with him) saying: I heard four things from Allah's Messenger (ﷺ) which impressed me and captivated me (and one out of these is this), that he forbade a woman to undertake journey extending over two days but with her husband, or with a Mahram; and he then narrated the rest of the hadith.

وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ عَبْدِ الْمَلِكِ بْنِ، عُمَيْرٍ قَالَ سَمِعْتُ قَزَعَةَ، قَالَ سَمِعْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ، قَالَ سَمِعْتُ مِنْ، رَسُولِ اللَّهِ صلى الله عليه وسلم أَرْبَعًا فَأَعْجَبْنَنِي وَآنَقْنَنِي نَهَى أَنْ تُسَافِرَ الْمَرْأَةُ مَسِيرَةَ يَوْمَيْنِ إِلاَّ وَمَعَهَا زَوْجُهَا أَوْ ذُو مَحْرَمٍ ‏.‏ وَاقْتَصَّ بَاقِيَ الْحَدِيثِ ‏.‏

References2 variants
In-Book Reference
Book 15, Hadith 466
USC-MSA web (English) reference
Book 7, Hadith 3100 (deprecated numbering scheme)