Sahih Muslim | Book 19 | Chapter 8

Narrated by 'Abdullah
It is narrated on the authority of 'Abdullah that a woman was found killed in one of the battles fought by the Messenger of Allah (may peace be upon him). He disapproved of the killing of women and children.
Narrated by Ibn 'Umar
It is narrated by Ibn 'Umar that a woman was found killed in one of these battles; so the Messenger of Allah (may peace be upon him) forbade the killing of women and children.