Narrated Ibn `Abbas:The Prophet (ﷺ) 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 Messenger (ﷺ)! I intend to go to such and such an army and my wife wants to perform Hajj." The Prophet (ﷺ) said (to him), "Go along with her (to Hajj).
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 ".
Bukhari
Penalty of Hunting while on Pilgrimage • Hadith 42