the author says: 'perhaps, the reason that Allah will make them alive is that they may give allegiance to Mahdi and as said before.
the author of 'esaaf-ur-rhagebeen' mentions that as per of traditions they shall be among his helpers and companions.'
«Mahdi is the proof [hujjat] of Allah»
the author of «yanabi-ul-muwadda» narrates (on page 448) from the book 'fara'ed-us-semtain' of hassan-ibn-khalid and he, from ali-ibn-musa ar-ridha (a.s.) who said: 'the one who is not pious, has no religion. verily the most honourable amongst you before Allah is the one who is the most pious.' thereafter he said: 'the fourth from my offspring is the son of the chief of slave-girls. through him, Allah shall clean the earth of every cruelty and oppression. he is the same one in whom people will doubt his birth and for him there will be an occultation. whenever he shall emerge, the earth will be illuminated by the divine light and the scale of justice will be established amongst the people such that no one will oppress the other. verily, he is the one for whom the earth will roll and there is no shadow for him. he is the one with regards to whom a caller from the heavens will call out and all the inhabitants of the earth will hear. be aware that the proof (hujjat) of Allah has emerged near the house of Allah. therefore follow him as truth is in him and with him.'
«Mahdi and completion of religion»
ibn-hajar in his «sawa'eq» (page 97) narrates from abul-qasim tabarani that the holy prophet (s.a.w.a.) said: Mahdi is from us. religion shall find its completion through him just as it found its expansion through us.'
the author of 'esaaf-ur-rhagebeen' too has narrated the same tradition on page 148 of his afore-said book.
sayyid mu'min-ibn-hassan shablanji in «nur-ul-absar» narrates (on page 231) from ali-ibn abi talib (peace be upon him) who said: i asked the messenger of Allah whether Mahdi is from us, the family of muhammad or from some other family. he replied: no. rather he shall be from us. through him, Allah shall bring the religion to its completion just as he had expanded it through us.(80)
this matter is further strengthened by numerous 'mustafiza' traditions which give indication to this fact that religion shall not come to its stage of completion until twelve caliphs come and pass over it. as research shows, you already know as to what ibn-abil hadeed has narrated about the consensus of the muslims on this fact and that is the duties shall not cease but with Mahdi. thus he is the last of the legatees and the religion of islam shall terminate in him just as his great grand-father was the last of the prophets and religion commenced from him.
«Mahdi is the twelfth caliph»