What is the obligatory expiation for a Zihar offender who cannot fast?

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The consensus among scholars is that if the person performing Zihar cannot find a slave to free and is unable to fast, the obligation shifts to feeding sixty poor persons, as commanded by God in His Book and established by the Sunnah of the Prophet. This inability may stem from old age, an illness where fasting would slow recovery or worsen the condition, or intense sexual desire (shabaq) that prevents abstinence from intercourse. Evidence includes the case of Aws ibn Al-Samit, whose wife testified to his advanced age, prompting the Prophet to command feeding sixty poor persons instead of fasting. Similarly, Salama ibn Sakhr was directed to feeding after mentioning his intense desire prevented him from fasting.