Is authorization permissible for Khul' (redemption from marriage) for both spouses or either one individually?

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Authorization is valid for Khul' from either the husband or the wife, or from one of them alone. Any person legally capable of disposing of Khul' for themselves may appoint an agent or be appointed as an agent for Khul'. This capacity applies whether the person is a freeman or a slave, male or female, Muslim or non-Muslim, restricted (mahjur) or rational (rashid). This is the established doctrine of Al-Shafi'i and the Ahl al-Ra'y, and there is no known disagreement concerning this principle.