What is the ruling when a man with two wives, Hafsa and Umra, calls Hafsa, but Umra responds, and he says 'You are divorced'?

Supporting text

If the husband clarifies by saying he only addressed Hafsa with the statement 'You are divorced,' then only Hafsa is divorced, provided she was present. If he states that he knew the respondent was Umra but intended to divorce Hafsa, then both wives are divorced according to the consensus of the scholars. If he states he thought the respondent was Hafsa but intended to divorce Hafsa, Hafsa is divorced based on one narration. Regarding Umra in this case, there are two narrations: one states she is also divorced, held by Al-Nakha'i, Qatada, Al-Awza'i, and the Ashab al-Ra'y (Proponents of Ra'y), and favored by Ibn Hamid, because he addressed her with the divorce formula, and she was a valid recipient (mahall), thus she is divorced as if he intended her directly. The second narration states she is not divorced, supported by Al-Hasan, Al-Zuhri, and Abu Ubayd. Imam Ahmad, in one narration, stated that both are divorced based on Ibrahim's view. Al-Hasan maintains only the intended wife is divorced, arguing the divorce was not directed at the other, similar to an accidental utterance. Abu Bakr states Ahmad's position clearly excludes the divorce of the non-intended wife. Imam Al-Shafi'i holds that only the responding wife (Umra) is divorced because she was addressed with the pronouncement, but the intended wife (Hafsa) is not divorced because she was not addressed, which contradicts the scenario where knowledge makes both divorced by intent. The absent wife is intended by the divorce wording, so she is divorced.