What is the ruling when a person vows to perform Hajj in the current year but fails to do so due to an excuse or other reason?

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If a person states, 'It is incumbent upon me for Allah that I perform Hajj in this year of mine' (Lillahi 'alayya al-Hajj fi 'aami hadha) and subsequently fails to perform Hajj, whether due to an excuse or not, both making up the Hajj (Qada) and offering expiation (Kaffarah) are obligatory upon him. The basis for this ruling is that the vowed Hajj was missed, thus necessitating its fulfillment (Qada), just as in the case of illness. Furthermore, the vow is understood to be conditional upon the prescribed action (Mashru' in the beginning); if the prescribed action is missed, its fulfillment becomes obligatory, and the same applies to the vowed action.