Sa'id bin Amr al-Qurashi (may Allah have mercy on him) narrates from Sayyidah Umm Kabshah (may Allah be pleased with her), a woman of Banu Udhrah, that she said: "O Messenger of Allah (peace and blessings be upon him), permit me to go out with such-and-such army." He (peace and blessings be upon him) said: "No." She said: "O Prophet of Allah (peace and blessings be upon him), I do not intend to fight; I only want to treat the wounded and the sick." He (peace and blessings be upon him) said: "Were it not for the fear that it would become a sunnah (a set practice) and it would be said that so-and-so woman also went out (for battle), I would certainly have given you permission."
This hadith is narrated from Sayyidah Umm Kabshah (may Allah be pleased with her) only with this chain, and al-Hasan bin Salih (may Allah have mercy on him) is alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب العين / 4443
Hadith Takhrij«أخرجه ابن أبي شيبة فى «مصنفه» برقم: 34341، والطبراني فى «الكبير» برقم: 431»