Musannaf Ibn Abi Shayba 28:1125

Humaid ibn Abd al-Rahman narrated to us, from Hassan, from al-Aswad ibn Qays, who said: Sa'id ibn Amr al-Qurashi narrated to me that Umm Kabshah, a woman from Banu Udhrah of Quda'ah, said: "O Messenger of Allah, permit me to go out with such-and-such army." He said: "No." I said: "O Messenger of Allah, I do not intend to fight; I only intend to treat the wounded and the sick, or to give water to the sick." He said: "Were it not that it would become a tradition, and it would be said that so-and-so went out, I would have permitted you. But sit."