If a muʿtakif dies in the middle of an iʿtikāf that has become obligatory on account of a vow, oath, covenant, or the passing of two days of iʿtikāf, it is not obligatory for his guardian (walī) (i.e. the eldest son) to make up the qaḍāʾ iʿtikāf, although the recommended precaution is that a qaḍāʾ iʿtikāf of a deceased person should be performed.
Of course, in the event that a muʿtakif had stipulated in his will that in such a case someone must be hired from the one-third of his estate[4] to perform iʿtikāf for him, then the deceased muʿtakif’s will must be followed.