Musannaf Ibn Abi Shayba 28:595

Mu'adh narrated to us, from Ash'ath, from al-Hasan, who said: He used to dislike that the elderly man, the young child, and the woman be killed in the Abode of War (Dar al-Harb). And he used to dislike for a man, if he carried anything of these (people) with him and it became heavy upon him, that he should cast it (abandon it) on the road.