The Prophet ﷺ said, "A woman should not travel for more than three days except with a Dhi-Mahram (i.e. a male with whom she cannot marry at all, e.g. her brother, father, grandfather, etc.) or her own husband.)"  

قُلْتُ لأَبِي أُسَامَةَ حَدَّثَكُمْ عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ ؓ أَنَّ النَّبِيَّ ﷺ قَالَ لاَ تُسَافِرِ الْمَرْأَةُ ثَلاَثَةَ أَيَّامٍ إِلاَّ مَعَ ذِي مَحْرَمٍ  

It is narrated by Ibn 'Umar that a woman was found killed in one of these battles; so the Messenger of Allah ﷺ forbade the killing of women and children.  

وُجِدَتِ امْرَأَةٌ مَقْتُولَةً فِي بَعْضِ تِلْكَ الْمَغَازِي فَنَهَى رَسُولُ اللَّهِ ﷺ عَنْ قَتْلِ النِّسَاءِ وَالصِّبْيَانِ  

‘Abd Allaah bin (mas’ud) said “A woman was found slain in one of the battles of the Apostle of Allaah ﷺ. The Apostle of Allaah ﷺ forbade to kill women and children. (Using translation from Abū Dāʾūd 2668)   

وُجِدَ فِي بَعْضِ مَغَازِي رَسُولِ اللَّهِ ﷺ امْرَأَةٌ مَقْتُولَةٌ «فَنَهَى رَسُولُ اللَّهِ ﷺ عَنْ قَتْلِ النِّسَاءِ وَالصِّبْيَانِ»