What is the ruling on the Kaffarah for breaking a vowed fast when the expiation itself requires fasting?

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If a Kaffarah is incurred for breaking one or more days of the vowed fast, and that Kaffarah requires fasting, there is a potential view that the Kaffarah fasting is not obligatory. This is because fulfilling the expiatory fast requires abandoning the vowed fast, and abandoning the vowed fast requires a Kaffarah, leading to an infinite regress (Tasalsul), or it implies abandoning the vow entirely. Another potential view holds that the Kaffarah is obligatory, but the means of fulfilling it (fasting) does not itself trigger another Kaffarah, as abandoning the vowed fast due to an excuse does not typically necessitate an expiation, thus avoiding the infinite regress.