The Prophet ﷺ said, "A woman may grant protection on behalf of the people," meaning she may grant protection that is binding upon the Muslims.
عن النبي ﷺ قال: إن المرأة لتأخذ للقوم يعني تجير على المسلمين.
Tirmidhi narrated it (1579) from Yahya bin Aktham, who said, Abdul-Aziz bin Abu Hazim narrated to us, from Kathir bin Zayd, from Walid bin Rabah, from Abu Hurairah, and he related it.Its chain is hasan because of Kathir bin Zayd Aslami and Walid bin Rabah, for both of them make the hadith hasan. Tirmidhi said, "This is a hasan gharib hadith. I asked Muhammad, and he said, 'This is a sahih hadith, and Kathir bin Zayd did hear from Walid bin Rabah, and Walid bin Rabah heard from Abu Hurairah, and he is close to reliable in his hadith.'"Hakim narrated it (2/41) through the route of Ibrahim bin Hamza Zubayri, from Abdul-Aziz bin Abu Hazim, with the same chain, with the wording, "The lowest of my nation may grant protection."Ahmad narrated it (8780) through the route of Sulayman bin Bilal, from Kathir bin Zayd, with the same chain, with the same wording as Hakim's version.