Is expiation (kaffarah) obligatory for a wife who, forgetfully, revealed a secret she had sworn not to disclose?

There is no expiation for the wife if she reveals a secret forgetfully, because for expiation to be obligatory, it is a condition that the oath must be binding upon a future, possible matter, that one swears voluntarily, and that one breaks the oath voluntarily and rememberingly. As for breaking an oath forgetfully, there is no expiation for it, and the proof for this is Allah’s saying: (Our Lord, do not impose blame upon us if we have forgotten or erred) and the Prophet, peace and blessings be upon him, said: (Indeed, Allah has overlooked for my Ummah errors, forgetfulness, and what they are coerced into).