It has been narrated on the authority of Anas b. Malik who said that the Messenger of Allah (ﷺ) allowed Umm Sulaim and some other women of the Ansar to accompany him when he went to war; they would give water (to the soldiers) and would treat the wounded.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا جَعْفَرُ بْنُ سُلَيْمَانَ، عَنْ ثَابِتٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَغْزُو بِأُمِّ سُلَيْمٍ وَنِسْوَةٍ مِنَ الأَنْصَارِ مَعَهُ إِذَا غَزَا فَيَسْقِينَ الْمَاءَ وَيُدَاوِينَ الْجَرْحَى .
Muslim
The Book ofJihadand Expeditions • Hadith 164