Sahih Bukhari Volume 3, Book 28, Hadith 1863

حَدَّثَنَا أَبُو النُّعْمَانِ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ عَمْرٍو، عَنْ أَبِي مَعْبَدٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ لاَ تُسَافِرِ الْمَرْأَةُ إِلاَّ مَعَ ذِي مَحْرَمٍ، وَلاَ يَدْخُلُ عَلَيْهَا رَجُلٌ إِلاَّ وَمَعَهَا مَحْرَمٌ ‏"‏‏.‏ فَقَالَ رَجُلٌ يَا رَسُولَ اللَّهِ إِنِّي أُرِيدُ أَنْ أَخْرُجَ فِي جَيْشِ كَذَا وَكَذَا، وَامْرَأَتِي تُرِيدُ الْحَجَّ‏.‏ فَقَالَ ‏"‏ اخْرُجْ مَعَهَا ‏"‏‏

Narrated By Ibn 'Abbas : The Prophet said, "A woman should not travel except with a Dhu-Mahram (her husband or a man with whom that woman cannot marry at all according to the Islamic Jurisprudence), and no man may visit her except in the presence of a Dhu-Mahram." A man got up and said, "O Allah's Apostle! I intend to go to such and such an army and my wife wants to perform Hajj." The Prophet said (to him), "Go along with her (to Hajj)."