She was fasting, and the Messenger of Allah ﷺ said: "The voluntary fasting person is the trustee of his own self; if he wishes, he fasts, and if he wishes, he breaks his fast." (1)

Shu'bah said: I said to him: "Did you hear this from Umm Hani'?" He said: "No, Abu Salih and our family informed me from Umm Hani'."

And Hammad ibn Salamah narrated this hadith from Simak ibn Harb, and he said: "From Harun, the son of Umm Hani's daughter (2), from Umm Hani'."

And the narration of Shu'bah is better.

Thus Mahmud ibn Ghaylan narrated to us from Abu Dawud, and he said: "The trustee of his own self." And someone other than Mahmud narrated to us from Abu Dawud, and he said: "The commander, or the trustee of his own self," with doubt. And thus it was narrated from more than one path from Shu'bah: "The commander, or the trustee of his own self," with doubt.

35 - Chapter on the voluntary fasting without making the intention the night before

742 - Hannad narrated to us, he said: Waki' narrated to us, from Talhah ibn Yahya, from his paternal aunt--------------------------------------------

(1) Its chain is weak like the preceding one. Al-Hakim narrated it in "Al-Mustadrak" 1/439 via the path of Simak ibn Harb, from Abu Salih, from Umm Hani'. He declared its chain authentic, and al-Dhahabi and al-Albani agreed with him in "Adab al-Zifaf" p. 156, and this is a clear error, for Abu Salih — whose name is Badham, the freed slave of Umm Hani' — is weak and a mudallis (one who conceals defects in narration).
And see the detailed discussion on the weakness of this hadith in our commentary on "Sharh al-Sunnah" 6/371.

(2) He is unknown (majhul) as stated in "Al-Taqrib."