I'tikaf (Islamic Ritual Retreat) by Proxy for the Dead in Islamic Fiqh

Based on the primary maxim it is necessary that the Islamic devotional practice to be done by the accountable person himself and a proxy to do those practices for someone else is not allowed. One of these devotional practice is i'tikaf (Arabic: اعتکاف Islamic Ritual Retreat) which is not an exceptional. Sometimes this devotion (Islamic worship) as Nazr (Arabic: نذر a vow or commitment to carry out an act) and like it has been obliged on the accountable and he does not do it and dies and owes a duty to do that. Now the question is if it is allowed (lawful) to the authority to perform for this missed i'tikaf as a proxy for him and in this case, the dead obligation (duty) has been fulfilled by this proxy. From the point of view of Imāmīyyah (Arabic: إمامیه) there are two opinions: an opinion which has not accepted this proxy and an opinion which has agreed to take this proxy that this opinion seems to be more appropriate in line with evidences. there are different opinions in four schools of Sunni Islam. From the view of Ḥanbalī if this missed i'tikaf is because of the obliged vow the dead authority must perform it as a proxy for the dead. Ḥanafī and Mālikī believe that the proxy for the dead is not valid and for it the food should be provided for the poor and Shafi'i has two opinions: the old opinion believes the validity of the authority to be a proxy for the dead and the modern attitude which believes that the food should be provided for the poor. Observing the few hadiths for the lack of validity and the multiplicity of hadiths and being on firm ground for the validity and of the authority i'tikaf, the opinion of the validity in Sunni school seems more acceptable and reasonable.