Sayyiduna Rabah bin al-Rabi' (may Allah be pleased with him) narrated: We were with the Prophet (peace and blessings be upon him) on a military expedition, and we saw that the people had gathered around a woman who had been killed. He (peace and blessings be upon him) said: "This one was not fighting." Then he said: "Who is in command of the vanguard?" The people said: Khalid bin al-Walid. So he (peace and blessings be upon him) sent a man to him and said: "Order Khalid not to kill any child or hired labourer."
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4606