It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) saw a slain woman in one of the battles, so he forbade the killing of women and children.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5753
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لضعف سليمان بن قرم.