Is it permissible to fast the days of Tashriq for an obligatory fast?

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There are two views regarding fasting the days of Tashriq for an obligatory fast. One is that it is not permissible because they are forbidden days, making it analogous to the Eid days. The second view is that the obligatory fast is valid, based on the report from Ibn Umar and Aisha permitting fasting for the one who cannot afford the Hady (which is generalized to all obligatory fasts).