Sayyiduna Hanzalah al-Katib (may Allah be pleased with him) narrates: We were on a military expedition with the Messenger of Allah (peace and blessings be upon him), and we passed by a woman who had been killed, with people gathered around her. The people made way for the Prophet (peace and blessings be upon him), and he ((peace and blessings be upon him)) said: "This one was not one who would fight." Then he said: "Go and catch up with Khalid bin al-Walid and tell him: he must not kill any child nor any hired labourer."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3476