What is the truth regarding what is narrated about the female Companion Rufaydah Al-Aslamiyah concerning her being the first nurse in Islam and her participation in battles with the Prophet, may God’s prayers and peace be upon him?

The noble female Companion is Rufaydah Al-Aslamiyyah. She had a tent in the Prophet's Mosque, may Allah's peace and blessings be upon him, where she treated the sick and wounded, as happened with Sa'd ibn Mu'adh, may Allah be pleased with him, on the Day of the Trench.

Rufaydah was not the only one who treated the wounded; there were other female Companions such as Umm 'Atiyyah, Al-Rubayyi' bint Mu'awwidh, Umm Sulaym, and others. They used to go out with the Prophet, may Allah's peace and blessings be upon him, in battles to provide water, treat the wounded, and take their share from the spoils of war.

As for the ruling on a woman treating a man, the basic principle is prohibition due to the looking and touching involved. However, it was permitted in war out of necessity, and necessity is estimated according to its extent.